Pneumatic down-the-hole hammer hole-forming backflusher and method of use

Abstract

The application belongs to the technical field of borehole deslagging, and discloses a reverse blower for pneumatic down-the-hole hammer hole forming and a use method. The reverse blower, the down-the-hole hammer, and the drill rod are lifted by a certain distance. At this time, the outer tube cylinder body slides downward by a distance under the action of gravity and the gravity of the down-the-hole hammer, so that the upper air hole corresponds to the reverse blowing hole, and the lower air hole is blocked by the upper air hole. At this time, the gas in the drill rod directly acts on the drilling channel through the upper air hole and the reverse blowing hole, and most of the high-pressure gas in the drill rod acts on the reverse blowing hole and can continuously blow the deposited drill cuttings, so that the accumulated cuttings are gradually removed, thereby reducing the influence of the rock fracture zone on the drill cuttings deslagging.

Description

Technical Field

[0001] This invention belongs to the field of drilling slag removal technology, specifically relating to a backflush device for pneumatic down-the-hole hammer drilling and its usage method. Background Technology

[0002] When using a pneumatic down-the-hole hammer for rock impact drilling, if the rock formation has developed fissures, the high-pressure air ejected from the down-the-hole hammer will leak out from the fissures, significantly reducing the airflow in the hole above the fissure section. Furthermore, the duration of the gas ejected from the down-the-hole hammer is relatively short, causing the drill cuttings to be unable to be effectively returned and discharged from the borehole. As a result, a large amount of drill cuttings accumulate in the borehole, which can easily lead to engineering accidents such as stuck drill or buried drill.

[0003] A typical drill string structure for pneumatic down-the-hole hammer drilling is "active drill rod + drill rod + pneumatic down-the-hole hammer impactor". When drill cuttings cannot be effectively returned for removal, the usual approach is to forcibly sweep back and forth in an attempt to solve the problem, but this is time-consuming, labor-intensive, and ineffective. Existing improvements often involve replacing ordinary drill rods with auger drill rods, but auger drill rods are expensive, have heavy mechanical loads, low drilling efficiency, and generally poor results. Another approach is to use a double-tube reverse circulation casing drilling method, with a drill string structure of "active drill rod + concentric double tubes + specialized down-the-hole hammer drill bit". This can solve the problem more easily, but the cost of this structure is too high, significantly increasing the cost of engineering construction. Summary of the Invention

[0004] The present invention aims to provide a backflush device and a method of use for pneumatic down-the-hole hammer drilling, so as to provide a backflush structure that is simple to operate and low in cost, so as to blow away and discharge the drill cuttings deposited above the down-the-hole hammer, thereby reducing the occurrence of drill bit burial.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a pneumatic down-the-hole hammer hole-forming backflush device, comprising... The outer cylinder body has a mating section, an upper venting section, a lower venting section and a connecting section arranged from top to bottom. The diameter of the lower venting section is larger than that of the upper venting section, and the side wall of the upper venting section is provided with a backflush hole. The inner tube cylinder body has an air guide cap installed at the bottom. The outer wall of the inner tube cylinder body has a lower air vent and an upper air vent symmetrically opened in the radial direction. The position of the lower air vent corresponds to the position of the air guide cap. The inner tube cylinder body is slidably inserted into the mating section and the upper air vent section, and the bottom of the inner tube cylinder body extends into the lower air vent section. The inner tube cylinder body is connected to the mating section in a driving connection. A sealing ring is provided between the inner wall of the upper air vent section and the outer wall of the inner tube cylinder body. The limiting component, installed on the upper ventilation section, is used to limit the sliding stroke of the inner tube cylinder. The centralizer is installed on the outer wall of the lower ventilation section.

[0006] The invention is further configured such that: the inner wall of the mating section is provided with a plurality of mating grooves along the circumferential direction; the outer wall of the inner tube cylinder is provided with a plurality of mating protrusions distributed at intervals along the circumferential direction; the mating protrusions slide in the mating grooves; the top of the inner tube cylinder has a hooking section; the outer diameter of the hooking section is the same as the outer diameter of the mating section; a buffer washer abuts against the top of the mating section; and the buffer washer is fixed to the hooking section.

[0007] The present invention is further configured such that: the limiting component includes a limiting pin and a guide groove, the outer wall of the upper venting section is threaded with the limiting pin, the head of the limiting pin is embedded in the side wall of the upper venting section, the side wall of the inner tube cylinder is provided with a guide groove, and the end of the limiting pin extends into the guide groove.

[0008] The invention is further configured such that the axes of the backflush hole and the upper vent hole are both inclined relative to the axis of the outer cylinder body, the width of the upper vent hole narrows from the inside to the outside, and the top of the outer opening of the backflush hole has a cut.

[0009] The invention is further configured such that: the bottom of the outer cylinder has a male connector and the top of the inner cylinder has a female connector.

[0010] The invention is further configured to include a storage component, which includes a storage compartment, a connecting rod, and a top rod. The lower end of the storage compartment has an inverted conical cross-section. Multiple connecting rods and top rods are provided and spaced apart at the bottom of the inner side of the storage compartment. The top of the connecting rod is fixed to the outer wall of the hanging section. The storage compartment is slidably fitted onto the outer wall of the upper ventilation section. The bottom edge of the outer opening of the backflush hole is not lower than the bottom edge of the inner side of the storage compartment. The outer wall of the upper ventilation section is provided with a shielding component. The top rod can drive the shielding component to slide upward, and the shielding component covers the backflush hole.

[0011] The invention is further configured such that: the shielding component includes a shielding cylinder and a driving edge, the outer wall of the upper ventilation section has a movable groove, the shielding cylinder is slidably fitted into the movable groove, the driving edge is fixed to the bottom of the shielding cylinder, the driving edge can abut against the top rod, and the driving edge slidably abuts against the side wall of the connecting rod.

[0012] The invention is further configured such that: the shielding component also includes a plurality of shielding arc plates, the shielding arc plates and the connecting rods are arranged at intervals, the two sides of the shielding arc plates are respectively fixed to two adjacent connecting rods, the bottom edge of the shielding arc plate can abut against the top edge of the driving side, and the top edge of the shielding arc plate is not higher than the top edge of the storage compartment.

[0013] The invention is further configured such that the storage compartment also has a plurality of spiral compartments arranged at intervals in the circumferential direction, and the spiral compartments are connected to the storage compartment.

[0014] This invention also discloses a method for using a backflush device for pneumatic down-the-hole hammer drilling: Q1. System assembly: Connect the top of the inner tube cylinder of the pneumatic down-the-hole hammer hole-forming backflush unit to the bottom of the drill rod, and connect the bottom of the outer tube cylinder to the top of the down-the-hole hammer. Q2. Start the drilling rig connected to the drill pipe to start drilling. The down-the-hole hammer goes down as the hole gets deeper. The bottom of the down-the-hole hammer is lifted by the bottom of the hole and transmitted to the outer tube cylinder. The overlap size of the inner tube cylinder and the outer tube cylinder reaches its maximum value. At this time, the backflush hole is blocked and covered by the side wall of the inner tube cylinder. The lower vent is located in the lower vent section. The gas in the drill pipe can enter the down-the-hole hammer through the inner tube cylinder, the lower vent, the lower vent section, and the connecting section in sequence to drive the down-the-hole hammer. The drill cuttings are carried back up by the airflow that exits the down-the-hole hammer. At this time, the shielding component seals the backflush hole, and the push rod is located below the backflush hole. Q3. Cuttings collection and storage: As the down-the-hole hammer descends into the borehole, it continuously blows air to remove cuttings. Cuttings that are not removed from the borehole will accumulate or sink. The sinking cuttings and the cuttings that collapse from the borehole wall can be collected in the collection bin to intercept and store the cuttings in the outer tube cylinder. Q4. Reverse blowing: The drilling rig stops working and lifts the down-the-hole hammer, outer tube cylinder, inner tube cylinder, and drill rod a certain distance. At this time, under the action of its own weight and the gravity of the down-the-hole hammer, the outer tube cylinder and the down-the-hole hammer will move downward relative to the inner tube cylinder and the collection bin until the maximum stroke is reached under the action of the limiting component. At this time, the overlap dimension of the inner tube cylinder and the outer tube cylinder reaches the minimum value, and the top rod lifting shielding component opens the back-blowing hole. The lower vent and the air guide cap are located in the upper venting section. The lower vent is blocked and covered by the side wall of the upper venting section. The position of the upper vent corresponds to the position of the back-blowing hole. At this time, the gas in the drill rod can flow to the outer tube cylinder through the upper vent and the back-blowing hole to blow away and discharge the accumulated drill cuttings in the collection bin.

[0015] This solution has at least the following beneficial effects: 1. By raising the drill pipe, backflush device, and down-the-hole hammer by a certain distance, the outer tube cylinder will slide down a certain distance relative to the inner tube cylinder under its own weight and the gravity of the down-the-hole hammer, thus aligning the upper vent hole with the backflush hole, and the lower vent hole being blocked by the upper vent section. At this time, the gas in the drill pipe acts directly on the borehole channel through the upper vent hole and the backflush hole, and most of the high-pressure gas in the drill pipe acts on the backflush hole, which can continuously blow away the deposited drill cuttings, thereby gradually removing the accumulated debris and reducing the impact of rock fracture zones on the removal of drill cuttings.

[0016] 2. By setting up upper and lower vents, high-pressure gas can smoothly reach the down-the-hole hammer through the lower vent during drilling to power its operation. At this time, the upper vent does not correspond to the backflush hole, making it difficult for drill cuttings to enter the space between the inner and outer cylinders through the backflush hole. When backflush is needed to remove cuttings, the device is lifted a certain distance, causing the outer cylinder to move relative to the inner cylinder under its own weight. At this point, the lower vent closes, the upper vent opens, and the down-the-hole hammer stops drilling. Most of the gas in the drill rod is discharged through the upper vent and backflush hole. This structure does not hinder the normal drilling of the down-the-hole hammer and can effectively utilize the high-pressure gas during drilling to backflush the drill cuttings.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] Figure 1 This is the front view of the present invention; Figure 2 for Figure 1 Enlarged view of point A in the image; Figure 3 for Figure 1 Enlarged isometric view of the central storage compartment (hiding the connecting rod and the shielding arc plate); Figure 4 for Figure 1 Top view of the central storage compartment (with the concealing curved panel hidden); Figure 5 for Figure 3 Cross-sectional view of section BB (hidden storage compartment and spiral compartment); Figure 6 for Figure 1 Top view of the cross-sectional structure at the intermediate joint section; Figure 7 This is a diagram illustrating another embodiment of the air-conducting cap in this invention; Figure 8 for Figure 1 Diagram of the outer tube structure (with hidden centralizer); Figure 9 for Figure 1 A structural diagram of the drilling state when connected to the down-the-hole hammer and drill pipe (1:3 scaled-down view). Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments: The reference numerals in the accompanying drawings include: 100. Outer cylinder body; 110. Mating section; 111. Mating groove; 120. Upper vent section; 121. Backflush hole; 122. Movable groove; 123. Cutout; 130. Lower vent section; 140. Connecting section; 150. Male connector; 160. Centralizer; 200. Inner cylinder body; 201. Lower vent; 202. Upper vent; 203. Mating protrusion; 204. Hook section; 205. Guide groove; 210. Air guide cap; 220. Sealing ring; 230. Buffer washer; 310. Limit pin; 410. Storage compartment; 420. Connecting rod; 430. Top rod; 440. Baffle plate; 450. Spiral compartment; 510. Shielding cylinder; 520. Driving edge; 600. Drill pipe; 700, Down-the-hole hammer.

[0020] Example: As attached Figure 1-4 As shown, this invention discloses a backflush device for pneumatic down-the-hole hammer drilling, comprising an outer tube cylinder 100, an inner tube cylinder 200, a limiting assembly, a centralizer 160, and a storage assembly. The outer tube cylinder 100 has a mating section 110, an upper air passage section 120, a lower air passage section 130, and a connecting section 140 arranged sequentially from top to bottom. The diameter of the lower air passage section 130 is larger than the diameter of the upper air passage section 120. A backflush hole 121 is provided on the side wall of the upper air passage section 120. The bottom of the outer tube cylinder 100 has a male connector 150, which can be connected to the female connector of the down-the-hole hammer 700, the female connector of the drill rod 600, or the female connector of the inner tube cylinder 200.

[0021] An air guide cap 210 is installed at the bottom of the inner tube cylinder 200. The outer wall of the inner tube cylinder 200 is symmetrically provided with a lower air vent 201 and an upper air vent 202 along the radial direction. The position of the lower air vent 201 corresponds to the position of the air guide cap 210. In this solution, the air guide cap 210 can be a structure with a conical top or a structure with circular cross-sections at both the top and bottom ends. When using the double-round-end air guide cap 210, the smooth end setting can more effectively reduce air resistance and kinetic energy loss, and it is connected to the bottom of the inner tube cylinder 200 by means of threaded engagement. The inner tube cylinder 200 is slidably inserted into the mating section 110 and the upper venting section 120, and the bottom of the inner tube cylinder 200 extends into the lower venting section 130. The inner tube cylinder 200 is connected to the mating section 110 in a driving connection. A sealing ring 220 is provided between the inner wall of the upper venting section 120 and the outer wall of the inner tube cylinder 200. The top of the inner tube cylinder 200 has a female connector end, which can be connected and installed with the male connector end 150 of the drill rod 600 and the male connector end 150 of the outer tube cylinder 100.

[0022] The connection method of the male end 150 and the female end is the same as the connection method of the drill rod 600 and the down-the-hole hammer 700. The purpose is to use a backflush device to replace one or more sections of the drill rod 600 without affecting the normal use of the down-the-hole hammer 700 and the drill rod 600.

[0023] The axes of both the backflush hole 121 and the upper vent hole 202 are inclined relative to the axis of the outer tube cylinder 100. Specifically, in the direction of the height of the axis of the outer tube cylinder 100, the height of the outer bottom edge of the hole is higher than the height of the inner bottom edge of the hole. The width of the upper vent hole 202 narrows from the inside to the outside. With this arrangement, when the gas in the inner tube cylinder 200 passes through the upper vent hole 202, the gas flowing out of the upper vent hole 202 is accelerated due to the gradually decreasing diameter of the upper vent hole 202, thus blowing away and expelling the deposited drill cuttings with a stronger impact force. The top of the outer opening of the backflush hole 121 has a cut 123. The opening 123 can be configured as an expansion section with a conical cross-section. Through the configuration of the opening 123, the jet accelerated by the upper vent 202 drives the surrounding air to form a negative pressure, which entrains the air and debris in the borehole channel to enhance the disturbance effect. The backflush hole 121 can also be configured as a venturi tube type cross-section, that is, the backflush hole 121 is an interface with a conical contraction at the inner end, a constant diameter in the middle, and a conical expansion at the opening 123. This allows the inner end of the backflush hole 121 to further accelerate the gas flow rate, guide and maintain the airflow in the middle, and finally expand and spray out from the opening 123 to achieve a better slag blowing and slag removal effect.

[0024] In the direction of the axis height of the outer tube cylinder 100, the height of the outer top edge of the lower vent 201 is lower than the height of the inner top edge of the hole. By restricting the tilt direction of the lower vent 201, the energy loss when the high pressure gas passes through the bottom of the inner tube cylinder 200 and enters the lower vent 201 is reduced, so as to ensure that the down-the-hole hammer 700 can be driven by sufficient air pressure.

[0025] A limiting assembly is installed on the upper venting section 120. The limiting assembly restricts the sliding stroke of the inner tube cylinder 200. The limiting assembly includes a limiting pin 310 and a guide groove 205. The limiting pin 310 is threaded into the outer wall of the upper venting section 120. The head of the limiting pin 310 is embedded in the side wall of the upper venting section 120. The guide groove 205 is formed on the side wall of the inner tube cylinder 200. The end of the limiting pin 310 extends into the guide groove 205. The limiting pin 310's end is positioned within the guide groove 205. The sliding mechanism of the 05-inch tube allows the limiting pin 310 to abut against the bottom of the guide groove 205, thereby hooking the outer tube cylinder 100 onto the inner tube cylinder 200. This ensures that the upper vent hole 202 on the inner tube cylinder 200 aligns with the backflush hole 121, while maintaining a stable position between the outer tube cylinder 100 and the inner tube cylinder 200. Furthermore, an anti-loosening gasket and a sealing structure are provided between the head of the limiting pin 310 and the outer tube cylinder 100 to prevent gas leakage or loosening at the limiting pin 310.

[0026] The centralizer 160 is located on the outer wall of the lower ventilation section 130. The centralizer 160 can be a spiral three-group centralizer 160. The centralizer 160 has a good centralizing effect to ensure that the backflush device is located in the middle of the borehole.

[0027] The inner wall of the mating section 110 is provided with multiple mating grooves 111 along the circumferential direction (together with the corresponding mating section 110, commonly known as a spline shaft). The outer wall of the inner tube cylinder 200 is provided with multiple spaced mating protrusions 203 along the circumferential direction (together with the corresponding inner tube cylinder 200, commonly known as a spline sleeve). The mating protrusions 203 slide in the mating grooves 111. Through this arrangement, the inner tube cylinder 200 and the outer tube cylinder 100 can only slide up and down. At the same time, the rotation of the inner tube cylinder 200 can be transmitted to the outer tube cylinder 100 through the mating protrusions 203 to drive the down-the-hole hammer 700 to rotate normally, ensuring the reliability and effectiveness of the transmission.

[0028] The top of the inner tube cylinder 200 has a hook section 204, the outer diameter of which is the same as the outer diameter of the mating section 110. The top of the mating section 110 abuts against a buffer washer 230, which can be made of polypropylene. The buffer washer 230 is fixed to the hook section 204. By setting the hook section, the maximum length of the inner tube cylinder 200 inserted into the outer tube cylinder 100 can be limited, that is, the maximum mating length between the inner tube cylinder 200 and the outer tube cylinder 100 can be limited. Combined with the minimum mating length setting of the upper limit component, the movement distance of the inner tube cylinder 200 relative to the outer tube cylinder 100 is effectively controllable. The setting of the buffer washer 230 can prevent the upward lifting force of the outer tube cylinder 100 from rigidly abutting against the hook section 204 of the inner tube cylinder 200 when drilling, thereby protecting the hook section 204 of the inner tube cylinder 200 and the top of the outer tube cylinder 100.

[0029] The storage assembly includes a storage bin 410, a connecting rod 420, and a top rod 430. The lower end of the storage bin 410 has an inverted conical cross-section, which guides the drill cuttings blown upwards during drilling with the down-the-hole hammer 700, preventing the flat bottom of the storage bin 410 from obstructing the upward discharge of drill cuttings. Multiple connecting rods 420 and top rods 430 are provided and spaced apart at the bottom of the inner side of the storage bin 410. The top of the connecting rod 420 is fixed to the outer wall of the hanging section 204. The storage bin 410 is slidably fitted onto the outer wall of the upper ventilation section 120. The bottom edge of the outer opening of the backflush hole 121 is not lower than the bottom edge of the inner side of the storage bin 410. The outer wall of the upper ventilation section 120 is provided with a shield. The component, push rod 430, can drive the shielding component to slide upward, and the shielding component covers the back-blowing hole 121. The width of push rod 430 is smaller than the outer diameter of back-blowing hole 121. In the attached diagram of this solution, the position of push rod 430 corresponds to the position of back-blowing hole 121 as an example. In practice, both connecting rod 420 and push rod 430 can be set to be staggered with back-blowing hole 121. That is, in actual use, connecting rod 420 and push rod 430 can completely not block back-blowing hole 121. The position shown in the figure is for reference only. The setting of the receiving bin can play a certain role in intercepting and collecting the sinking drill cuttings, avoiding all sinking drill cuttings from accumulating on down-the-hole hammer 700, thereby reducing the probability of drill cuttings burying the drill.

[0030] The shielding assembly includes a shielding cylinder 510 and a driving edge 520. The outer wall of the upper ventilation section 120 has a movable groove 122. The outer side of the backflush hole 121 is connected to the movable groove 122. The shielding cylinder 510 is slidably fitted into the movable groove 122. The driving edge 520 is fixed to the bottom of the shielding cylinder 510 and can abut against the top rod 430. The driving edge 520 slidably abuts against the side wall of the connecting rod 420. Through the setting of the shielding cylinder 510, when the down-the-hole hammer 700 is drilling, the shielding cylinder 510 can seal and protect the backflush hole 121 to prevent drill cuttings deposited in the collection bin 410 from clogging the backflush hole 121. When backflushing and slag removal are required, the entire device is lifted, so that the inner tube cylinder 200 is driven to collect the slag through the connecting rod 420. As the chamber 410 and push rod 430 rise, the push rod 430 contacts and lifts the drive edge 520 and the shielding cylinder 510, thus unblocking the backflush hole 121. Simultaneously, the upper vent 202 also gradually rises and aligns with the backflush hole 121, thereby blowing away the drill cuttings deposited in the chamber 410. Furthermore, the chamber 410's obstruction of the backflush hole 121, compared to the gas entering the borehole channel, locally increases the pressure emitted from the backflush hole 121. That is, when high-pressure gas is blown out of the backflush hole 121 and acts between the chamber 410 and the outer cylinder 100, the pressure is greater, allowing the drill cuttings to gain more initial lift. This facilitates the discharge of drill cuttings from the borehole channel and their dispersion by the high-pressure gas, preventing drill cuttings from accumulating and becoming stuck in the drill string. The shielding assembly also includes multiple shielding arc plates 440, which are arranged at intervals with the connecting rods 420. The two sides of the shielding arc plate 440 are fixed to the two adjacent connecting rods 420 respectively. The bottom edge of the shielding arc plate 440 can abut against the top edge of the driving edge 520, and the top edge of the shielding arc plate 440 is not higher than the top edge of the storage compartment 410. By setting the shielding arc plate 440, the top of the movable slot 122 can be shielded to prevent the drill cuttings in the collection bin 410 from accumulating on the top of the shielding cylinder 510 and interfering with the sliding of the shielding cylinder 510 relative to the movable slot 122. After the backflushing and slag removal is completed, if the drilling continues, the shielding cylinder 510 may not be able to slide smoothly to the bottom of the movable slot 122 due to the obstruction of some debris. During the process of the inner tube cylinder 200 driving the connecting rod 420 to move downward, the outer tube cylinder 100 cannot slide downward because it is in contact with the bottom of the drilling channel. At this time, the connecting rod 420 will drive the collection bin 410, the shielding arc plate 440 to slide downward relative to the shielding cylinder 510 and the outer tube cylinder 100. That is, the shielding arc plate 440 can guide the shielding cylinder 510 to slide to the bottom of the movable slot 122 by abutting the top surface of the driving edge 520, thereby resetting the movable slot 122. If only the shielding arc plate 440 is installed, it can also block the backflush hole 121. However, when the receiving chamber 410 and the shielding arc plate 440 move upward relative to the outer tube cylinder 100, the shielding arc plate 440 and the connecting rod 420 move synchronously. As a result, when the shielding arc plate 440 opens the backflush hole 121, the upper vent hole 202 is still a certain distance away from the backflush hole 121. That is, drill cuttings may enter between the inner tube cylinder 200 and the outer tube cylinder 100 through the backflush hole 121, thereby affecting the sliding of the inner tube cylinder 200 relative to the outer tube cylinder 100. By setting up the shielding arc plate 440 and the shielding cylinder 510 together, a better slag prevention effect can be achieved.

[0031] The receiving chamber 410 also has multiple spaced spiral chambers 450 circumferentially arranged. The spiral chambers 450 are connected to the receiving chamber 410. The outer diameter of the spiral chamber 450 is larger than the outer diameter of the receiving chamber 410 but smaller than the outer diameter of the centralizer 160. That is, the outer diameter of the spiral chamber 450 is smaller than the borehole diameter. The spiral chambers 450 expand the interception surface and capacity of the receiving chamber 410. Simultaneously, the spiral arrangement reduces the impact of the spiral chambers 450 on the slag discharge of the borehole channel, i.e., the down-the-hole hammer 70. The blown gas carries the drill cuttings upward and after hitting the outer surface of the auger chamber 450, the kinetic energy loss is small, and it can pass smoothly through the auger chamber 450. This avoids the auger chamber 450 affecting the pneumatic slag removal of the down-the-hole hammer 700. In addition, when the backflush hole 121 is in the conical section of the receiving chamber 410 during backflush slag removal, the blown gas can be guided and rotated by the auger chamber 450, so that the blown gas has a certain swirling effect, and thus has a better slag removal effect when blowing slag in the reverse direction.

[0032] How to use a pneumatic down-the-hole hammer blower for hole forming: Q1. System Assembly: Connect the top of the inner cylinder 200 of the pneumatic down-the-hole hammer 700 hole-forming backflush device to the bottom of the drill rod 600, and connect the bottom of the outer cylinder 100 to the top of the down-the-hole hammer 700. The outer cylinder 100, inner cylinder 200, limiting assembly, centralizer 160, and storage assembly together constitute the backflush device. In actual use, 1-3 backflush devices can be set, depending on the situation. The length of a single backflush device can be the length of the drill rod 600. By connecting multiple backflush devices, the number of backflush and slag removal nodes can be increased, so as to better blow the drill cuttings out of the borehole channel.

[0033] Q2. Start the drilling rig connected to the drill rod 600 to drill. The down-the-hole hammer 700 descends as the hole deepens. The bottom of the down-the-hole hammer 700 is lifted by the bottom of the hole and transmitted to the outer tube cylinder 100. The overlap size of the inner tube cylinder 200 and the outer tube cylinder 100 reaches its maximum value. At this time, the inner side of the backflush hole 121 is blocked and covered by the side wall of the inner tube cylinder 200, and the top of the movable groove 122 is blocked and covered by the blocking arc plate 440. The lower vent hole 201... Located within the lower ventilation section 130, the gas inside the drill rod 600 can sequentially pass through the inner tube cylinder 200, the lower ventilation hole 201, the lower ventilation section 130, and the connecting section 140 to enter the down-the-hole hammer 700 and drive the down-the-hole hammer 700 to work. The drill cuttings are carried upward by the airflow exiting the down-the-hole hammer 700. At this time, the shielding component seals the outside of the backflush hole 121, and the push rod 430 is located at a certain distance below the backflush hole 121 and does not come into contact with the drive edge 520. Q3. Slag collection and storage: The down-the-hole hammer 700 continuously blows air to remove slag during drilling. Drill cuttings that are not discharged from the drilling channel will accumulate or sink. Most of the sinking drill cuttings and slag from the collapse of the borehole wall can be collected in the collection bin 410 and the spiral bin 450 to intercept and store the drill cuttings and slag at the outer tube cylinder 100. Q4. Reverse blowing: The drilling rig stops working and lifts the down-the-hole hammer 700, outer cylinder 100, inner cylinder 200, and drill rod 600 a certain distance. At this time, under the action of its own weight and the gravity of the down-the-hole hammer 700, the outer cylinder 100 and the down-the-hole hammer 700 will move downward relative to the inner cylinder 200 and the receiving chamber 410 (the inner cylinder 200 moves upward relative to the down-the-hole hammer 700 and the outer cylinder 100 a certain distance), until the inner cylinder 200 reaches its maximum stroke relative to the outer cylinder 100 under the action of the limiting component, and the overlap dimension of the inner cylinder 200 and the outer cylinder 100 reaches its minimum value. During this process, the receiving chamber 410 moves synchronously. As the inner tube cylinder 200 moves upward, the bottom of the inner side of the collection chamber 410 is raised to the backflush hole 121, allowing the backflush hole 121 to more thoroughly blow away the drill cuttings stored in the collection chamber 410 and the spiral chamber 450. At the same time, the top rod 430 lifts the shielding assembly to open the backflush hole 121. The lower vent 201 and the air guide cap 210 are located inside the upper venting section 120. The lower vent 201 is blocked and covered by the side wall of the upper venting section 120. The position of the upper vent 202 corresponds to the position of the backflush hole 121. At this time, the gas in the drill rod 600 can flow through the upper vent 202 and the backflush hole 121 to the outside of the outer tube cylinder 100, so as to blow away and discharge the drill cuttings stored in the collection chamber 410.

[0034] If the drilling process is to be completely lifted, that is, without going down into the borehole, the high-pressure ventilation state can be maintained. In this way, the high-pressure gas can be continuously blown out from the collection chamber 410 and the spiral chamber 450, which can blow out the drill cuttings that have accumulated and blocked above the back blower, thereby preventing the drill from getting stuck or buried by the drill cuttings accumulated in the borehole channel during the lifting of the down-the-hole hammer 700.

[0035] If it is only for drilling and slag removal, after Q4, the drilling rig structure drives the drill rod 600, the backflush device and the down-the-hole hammer 700 to continue to descend. After the down-the-hole hammer 700 abuts against the bottom of the drilling channel, as the drill rod 600 and the inner tube channel continue to descend, the shielding arc plate 440 abuts against the driving edge 520 and slides down, causing the shielding cylinder 510 to seal the backflush hole 121. At the same time, the lower end of the inner tube cylinder 200 and the lower vent hole 201 slide from the upper vent section 120 to the lower vent section 130, so that the high-pressure air in the drill rod 600 can enter the down-the-hole hammer 700 from the inner tube cylinder 200, the lower vent hole 201, the lower vent section 130 and the connecting section 140.

[0036] Regarding the machining requirements for the outer cylinder body 100 and the inner cylinder body 200: Since the pneumatic down-the-hole hammer 700 generally operates at a medium to low air pressure (≤1MPa), its typical air consumption is 4-20m³ / h. 3To ensure effective cuttings removal, the annular return air velocity needs to be ≥15m / s (positive circulation). Therefore, the machining accuracy of the outer cylinder 100 and the inner cylinder 200 is required. These are two circular tubes, and the inner wall of the outer cylinder 100 and the outer wall of the inner cylinder 200 must be in close contact and able to slide against each other, while also possessing a certain air-sealing capacity to reduce air leakage at these points.

[0037] To address this requirement, a small-clearance sliding fit with a machined hole-based system, a metal micro-clearance, and an elastic sealing ring (220mm sealing ring in this design) is considered. Geometric tolerance requirements: Geometric tolerance error must be ≤ 1 / 3 of the dimensional tolerance to prevent sudden changes in local clearance from causing sealing ring failure. Surface roughness requirements (for the sliding fit and sealing ring assembly, using standard grinding precision): Inner cylinder body 200mm outer wall - Ra 0.8μm; outer cylinder body 100mm inner wall - Ra 1.6μm.

[0038] With an elastic sealing ring, it can meet the air sealing requirements of ≤1MPa during normal drilling.

[0039] Regarding the leakage consideration at the bottom air guide cap 210 of the backflushing device during backflushing: The air guide cap 210, during backflushing, seals the air passage to the downward air passage section 130 in conjunction with the inner tube cylinder 200. Due to structural limitations, an elastic sealing ring cannot be installed at this location. Therefore, complete air sealing cannot rely solely on the tightness between the inner wall of the outer tube cylinder 100 and the outer wall of the inner tube cylinder 200, resulting in a small amount of gas leakage. When the air pressure is ≤1MPa, the micro-gap between the inner wall of the outer tube cylinder 100 and the outer wall of the inner tube cylinder 200 is considered as incompressible laminar flow (extremely small gap, extremely weak flow capacity, low flow velocity, Reynolds number far less than 2300). The Hagen-Poiseuille law is used to calculate the laminar flow rate of the parallel plate with a fixed gap. The formula is: Calculations showed that the maximum leakage at the bottom was no more than 1%, and most of the gas leaked out through the backflush hole 121, which met the requirements.

[0040] The parts of the device not covered herein are the same as or can be implemented using existing technologies.

[0041] Among them, insert and sliding insert are mating bodies with holes, the cross section of the shaft or rod matches the hole, and the shaft or rod can slide relative to the hole. Threaded insert is a hole with threads, the shaft or rod is threaded, and the shaft or rod is connected to the mating body by screwing. Detachable installation can be by bolt thread connection or bolt and nut connection, etc., depending on what can be actually achieved.

[0042] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A backflush device for pneumatic down-the-hole hammer drilling, characterized in that: include The outer cylinder body has a mating section, an upper venting section, a lower venting section and a connecting section arranged from top to bottom. The diameter of the lower venting section is larger than that of the upper venting section, and the side wall of the upper venting section is provided with a backflush hole. The inner tube cylinder has an air guide cap installed at the bottom. The outer wall of the inner tube cylinder has a lower air vent and an upper air vent symmetrically opened in the radial direction. The position of the lower air vent corresponds to the position of the air guide cap. The inner tube cylinder is slidably inserted into the mating section and the upper air vent section, and the bottom of the inner tube cylinder extends into the lower air vent section. The inner tube cylinder is drivenly connected to the mating section. A sealing ring is provided between the inner wall of the upper air vent section and the outer wall of the inner tube cylinder. A limiting component is installed on the upper ventilation section, and the limiting component is used to limit the sliding stroke of the inner tube cylinder. The centralizer is installed on the outer wall of the lower ventilation section.

2. The pneumatic down-the-hole hammer reverse blower as described in claim 1, characterized in that: The inner wall of the mating section is provided with multiple mating grooves along the circumference, and the outer wall of the inner tube cylinder is provided with multiple spaced mating protrusions along the circumference. The mating protrusions slide in the mating grooves. The top of the inner tube cylinder has a hook section, the outer diameter of which is the same as the outer diameter of the mating section. A buffer washer is abutted against the top of the mating section, and the buffer washer is fixed to the hook section.

3. The pneumatic down-the-hole hammer reverse blower as described in claim 1, characterized in that: The limiting component includes a limiting pin and a guide groove. The outer wall of the upper venting section is threaded with a limiting pin. The head of the limiting pin is embedded in the side wall of the upper venting section. The side wall of the inner tube cylinder is provided with a guide groove, and the end of the limiting pin extends into the guide groove.

4. The pneumatic down-the-hole hammer reverse blower as described in claim 1, characterized in that: The axes of the backflush hole and the upper vent hole are both inclined relative to the axis of the outer cylinder body. The width of the upper vent hole narrows from the inside to the outside. The top of the outer opening of the backflush hole has a cut.

5. The pneumatic down-the-hole hammer reverse blower as described in claim 1, characterized in that: The bottom of the outer cylinder has a male connector, and the top of the inner cylinder has a female connector.

6. The pneumatic down-the-hole hammer reverse blower as described in claim 1, characterized in that: It also includes a storage assembly, which includes a storage compartment, a connecting rod, and a top rod. The lower end of the storage compartment has an inverted conical cross-section. Multiple connecting rods and top rods are provided and spaced apart at the bottom of the inner side of the storage compartment. The top of the connecting rod is fixed to the outer wall of the hanging section. The storage compartment is slidably fitted onto the outer wall of the upper ventilation section. The bottom edge of the outer opening of the backflush hole is not lower than the bottom edge of the inner side of the storage compartment. The outer wall of the upper ventilation section is provided with a shielding assembly. The top rod can drive the shielding assembly to slide upward, and the shielding assembly covers the backflush hole.

7. The pneumatic down-the-hole hammer reverse blower as described in claim 6, characterized in that: The shielding assembly includes a shielding cylinder and a driving edge. The outer wall of the upper ventilation section has a movable groove. The shielding cylinder is slidably fitted into the movable groove. The driving edge is fixed to the bottom of the shielding cylinder. The driving edge can abut against the top rod. The driving edge slidably abuts against the side wall of the connecting rod.

8. The pneumatic down-the-hole hammer hole-forming backflush device as described in claim 7, characterized in that: The shielding assembly also includes multiple shielding arc plates, which are arranged at intervals with the connecting rods. The two sides of each shielding arc plate are fixed to two adjacent connecting rods. The bottom edge of each shielding arc plate can abut against the top edge of the driving side, and the top edge of each shielding arc plate is not higher than the top edge of the storage compartment.

9. The pneumatic down-the-hole hammer reverse blower as described in claim 6, characterized in that: The storage compartment also has multiple spiral compartments arranged at intervals around its circumference, and the spiral compartments are connected to the storage compartment.

10. A method of using the pneumatic down-the-hole hammer hole-forming backflush device according to any one of claims 6-9, characterized in that: Q1. System assembly: Connect the top of the inner cylinder of the pneumatic down-the-hole hammer hole-forming backflush device to the bottom of the drill rod, and connect the bottom of the outer cylinder to the top of the down-the-hole hammer. Q2. Start the drilling rig connected to the drill pipe to start drilling. The down-the-hole hammer goes down as the hole gets deeper. The bottom of the down-the-hole hammer is lifted by the bottom of the hole and transmitted to the outer tube cylinder. The overlap size of the inner tube cylinder and the outer tube cylinder reaches its maximum value. At this time, the backflush hole is blocked and covered by the side wall of the inner tube cylinder. The lower vent is located in the lower vent section. The gas in the drill pipe can enter the down-the-hole hammer through the inner tube cylinder, the lower vent, the lower vent section, and the connecting section in sequence to drive the down-the-hole hammer. The drill cuttings are carried back up by the airflow that exits the down-the-hole hammer. At this time, the shielding component seals the backflush hole, and the push rod is located below the backflush hole. Q3. Cuttings collection and storage: As the down-the-hole hammer descends into the borehole, it continuously blows air to remove cuttings. Cuttings that are not removed from the borehole will accumulate or sink. The sinking cuttings and the cuttings that collapse from the borehole wall can be collected in the collection bin to intercept and store the cuttings in the outer tube cylinder. Q4. Reverse blowing: The drilling rig stops working and lifts the down-the-hole hammer, outer tube cylinder, inner tube cylinder, and drill rod a certain distance. At this time, under the action of its own weight and the gravity of the down-the-hole hammer, the outer tube cylinder and the down-the-hole hammer will move downward relative to the inner tube cylinder and the collection bin until the maximum stroke is reached under the action of the limiting component. At this time, the overlap dimension of the inner tube cylinder and the outer tube cylinder reaches the minimum value, and the top rod lifting shielding component opens the back-blowing hole. The lower vent and the air guide cap are located in the upper venting section. The lower vent is blocked and covered by the side wall of the upper venting section. The position of the upper vent corresponds to the position of the back-blowing hole. At this time, the gas in the drill rod can flow to the outer tube cylinder through the upper vent and the back-blowing hole to blow away and discharge the accumulated drill cuttings in the collection bin.

Images