An air hammer for drilling a well and a method of drilling a well

Abstract

The application relates to an air hammer for drilling and a drilling method, and belongs to the technical field of drilling. The air hammer comprises an outer shell body, a drill bit, a piston, a self-lubricating connector and an overrunning clutch which are arranged in the outer shell body; the drill bit and the piston are respectively provided with splines, and a spiral groove is arranged on the piston between the splines; the self-lubricating connector is provided with a spline groove, and the self-lubricating connector is movably connected with the drill bit and the piston through the cooperation of the splines and the spline groove; and the overrunning clutch is uniformly provided with spiral sample pieces which are slidably connected with the spiral groove. The air hammer can impact the drill bit and rotate the drill bit under the action of the overrunning clutch, and can effectively improve the drilling efficiency. The overrunning clutch can be idled when the piston returns upward, the load of the piston is reduced, the piston can quickly return, the impact frequency of the piston can be effectively increased, and the drilling efficiency is further improved. The problems that the existing air hammer only impacts to drill and the drilling efficiency is low are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to an air hammer for drilling and a drilling method, and belongs to the technical field of drilling. BACKGROUND

[0002] Air hammers are widely used in drilling, and have very high drilling speed and can prevent well leakage. At present, almost all air hammers use piston impact bit to drill holes by impacting the formation. For example, a single large-diameter reverse circulation air hammer for drilling large-size wellbores disclosed in patent application No. CN105113978A includes a double-wall conversion sub, a reverse circulation air hammer body and an anti-falling bit. The reverse circulation air hammer body includes an upper joint, an outer cylinder, a ring check valve, a central sand discharge pipe, a gas distribution inner cylinder, a pneumatic piston and a gas distribution sleeve. The upper joint and the double-wall conversion sub are connected by threads. The outer cylinder is connected with the spline sleeve of the anti-falling bit by threads. The gas distribution inner cylinder, the gas distribution sleeve and the clasp ring of the anti-falling bit are sequentially seated on the spline sleeve. The pneumatic piston is located in the cavity formed by the gas distribution inner cylinder and the gas distribution sleeve. The upper end of the central sand discharge pipe is inserted into the lower end of the inner pipe of the double-wall conversion sub. The middle large-diameter section is pressed into the gas distribution inner cylinder. The lower end is inserted into the upper end of the bit body of the anti-falling bit. The ring check valve is arranged between the central sand discharge pipe and the upper joint. The present application does not need to use a three-channel drill pipe, and also does not need the liquid column pressure of mud to assist sand discharge.

[0003] The above-mentioned air hammer can impact the formation to drill by impacting the bit. However, when drilling, it only impacts, the drilling method is single, and the efficiency is low. Therefore, it is necessary to redesign an air hammer for drilling and a drilling method to solve the above-mentioned problems. SUMMARY

[0004] The present application aims at the deficiencies of the prior art, and provides an air hammer for drilling and a drilling method which can effectively improve the drilling efficiency and quickly drill.

[0005] The technical scheme of the present application is as follows:

[0006] The utility model provides an air hammer for drilling well, including outer casing, upper joint, lower joint, drill bit and piston, the outer casing is cylindrical, the upper joint is installed on one end of the outer casing, the drill bit is movably installed on the other end of the outer casing through the lower joint, and the piston is arranged in the outer casing between the drill bit and the upper joint, characterized by: the top of the drill bit and the bottom of the piston are respectively provided with spline, and the piston is provided with helical groove between the spline, the self-lubricating connector is movably installed in the outer casing between the drill bit and the piston through the inner cylinder, the self-lubricating connector is provided with spline groove, and the self-lubricating connector is movably connected with the drill bit and the piston through the cooperation of the spline and the spline groove, the overrunning clutch is arranged in the outer casing above the self-lubricating connector, the inner wall of the overrunning clutch is evenly distributed with spiral sample, and the spiral sample is slidably connected with the helical groove.

[0007] The flange, spacer retainer, spacer and inner cylinder are sequentially sleeved on the piston above the overrunning clutch from bottom to top, the gas distribution valve is arranged on the top end face of the inner cylinder, the gas guide retainer is arranged on the gas distribution valve, and the check valve is arranged on the valve seat above the gas guide retainer.

[0008] The check valve comprises a valve rod, a valve head and a reset spring, the valve head is movably inserted on the top end face of the valve rod, and the reset spring is arranged between the valve head and the valve rod, the valve rod is in threaded connection with the valve seat, and the valve head above the valve rod is in sliding sealing connection with the upper joint.

[0009] The gas guide retainer is evenly distributed with flow-through holes, the valve seat around the valve rod is evenly distributed with axial holes in the form of a ring, and the axial holes are communicated with the annular space between the inner cylinder and the outer casing through the flow-through holes.

[0010] The upper sealing flange, middle sealing flange and lower sealing flange are sequentially arranged on the piston above the spline from top to bottom, the upper sealing flange and the middle sealing flange are in sliding sealing connection with the inner cylinder, and the lower sealing flange is in sliding sealing connection with the spacer.

[0011] The piston is provided with a piston center hole penetrating the piston, the cross section of the gas distribution valve is in the form of a T letter, and the guide rod at the bottom center of the gas distribution valve is in sealing connection with the piston center hole.

[0012] The inner cylinder between the upper sealing flange and the middle sealing flange is provided with radial holes, and the radial holes are respectively communicated with the annular space between the inner cylinder and the outer casing and the annular space between the piston and the inner cylinder.

[0013] The inner wall of the inner cylinder above the radial holes is provided with a gas distribution ring groove.

[0014] The spacer outside the lower sealing flange is provided with a shoulder, the shoulder is evenly distributed with spacer inner holes, and the annular space between the piston above the lower sealing flange and the spacer is communicated with the annular space between the piston below the lower sealing flange and the spacer through the spacer inner holes.

[0015] The radial communication holes are uniformly distributed on the piston circumference between the lower sealing flange and the spline, and respectively communicate with the piston central hole and the annular space between the lower sealing flange and the spacer sleeve.

[0016] The drill bit is provided with a drill bit central hole, a tail pipe is threadedly installed on the top end of the drill bit central hole, and the drill bit central hole communicates with the piston central hole through the tail pipe; and a plurality of exhaust holes are connected to the bottom end of the drill bit central hole.

[0017] The inner wall of the lower joint is provided with an inner flange, and an anti-falling check ring is threadedly installed on the drill bit above the inner flange.

[0018] The overrunning clutch comprises a sleeve, a pawl wheel and a sliding pin.

[0019] The beneficial effects of the present application are:

[0020] The air hammer for drilling can impact the drill bit when the piston is in downward stroke, and can drive the drill bit to rotate under the action of the overrunning clutch, so that the drill bit can be drilled and impacted at the same time, thereby effectively improving the drilling efficiency. The overrunning clutch can be idled when the piston is in upward stroke, thereby reducing the load of the piston, enabling the piston to quickly return, and effectively increasing the impact frequency of the piston, and further improving the drilling efficiency. The problem of low drilling efficiency caused by the existing air hammer only through impact is solved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural schematic diagram of the present application;

[0022] Figure 2 is a structural schematic diagram of the piston of the present application;

[0023] Figure 3 is a structural schematic diagram of the drill bit of the present application;

[0024] Figure 4 is a structural schematic diagram of the self-lubricating connector of the present application;

[0025] Figure 5 is Figure 1 is an enlarged schematic diagram of position A in FIG.

[0026] Figure 6 is Figure 1 is an enlarged schematic diagram of position B in FIG.

[0027] Figure 7 is a structural schematic diagram of the overrunning clutch of the present application;

[0028] Figure 8 is a stroke state schematic diagram of the piston of the present application;

[0029] Figure 9is a schematic diagram of the return state of the piston of the present application.

[0030] In the figure: 1, outer shell, 2, upper joint, 3, lower joint, 4, drill bit, 5, piston, 6, spline, 7, helical groove, 8, inner cylinder, 9, self-lubricating connector, 10, spline groove, 11, overrunning clutch, 12, spiral spline, 13, spacer retainer, 14, spacer, 15, inner cylinder, 16, valve, 17, gas guide retainer, 18, valve seat, 19, valve stem, 20, valve head, 21, return spring, 22, flow-through hole, 23, axial hole, 24, upper sealing flange, 25, middle sealing flange, 26, lower sealing flange, 27, piston center hole, 28, radial hole, 29, spacer inner hole, 30, radial communication hole, 31, drill bit center hole, 32, tail pipe, 33, exhaust hole, 34, inner flange, 35, anti-disengagement retainer, 36, sleeve, 37, pawl wheel, 38, sliding pin, 39, flange, 40, pin, 41, valve ring groove. DETAILED DESCRIPTION

[0031] The air hammer for drilling, comprising an outer shell 1, an upper joint 2, a lower joint 3, a drill bit 4 and a piston 5, the outer shell 1 is in a cylindrical shape, one end of the outer shell 1 is threadedly installed with the upper joint 2 to connect the upper pipe string through the upper joint 2. The other end of the outer shell 1 is movably installed with the drill bit 4 through the lower joint 3, and the piston 5 is arranged in the outer shell 1 between the drill bit 4 and the upper joint 2. The piston 5 is used to repeatedly impact the drill bit 4 through the piston 5 under the pushing of high-pressure gas, so as to drill the drill bit 4 in the form of impact.

[0032] The top end of the drill bit 4 and the bottom end of the piston 5 are respectively provided with splines 6, and a helical groove 7 is arranged on the piston 5 between the splines 6; a self-lubricating connector 9 is movably arranged in the inner shell 1 between the drill bit 4 and the piston 5 through an inner cylinder 8, the self-lubricating connector 9 is provided with a spline groove 10, and the self-lubricating connector 9 is movably connected with the drill bit 4 and the piston 5 through the cooperation of the splines 6 and the spline groove 10. The piston 5 can move axially relative to the self-lubricating connector 9 through the splines 6 and the spline groove 10, and then the piston 5 can impact the drill bit 4 through the axial movement, so that the drill bit 4 impacts the formation; at the same time, the piston 5 can drive the self-lubricating connector 9 to rotate through the splines 6, and then the self-lubricating connector 9 drives the drill bit 4 to rotate through the spline groove 10 and the splines 6 in the process of rotating the self-lubricating connector 9, so that the drill bit 4 can rotate and drill into the formation; thus, the piston 5 can drive the drill bit 4 to rotate in the process of impacting the drill bit 4 through the self-lubricating connector 9 and the splines 6 and the spline groove 10, so that the drill bit 4 can rotate and drill into the formation in the process of impacting the formation, which can effectively improve the drilling efficiency compared with the drilling method through only impact. The outer shell 1 above the self-lubricating connector 9 is provided with an overrunning clutch 11, and the overrunning clutch 11 includes a sleeve 36, a pawl wheel 37 and a slide pin 38. The inner wall of the overrunning clutch 11 is uniformly provided with a helical sample 12, and the helical sample 12 is slidably connected with the helical groove 7. Due to the characteristics of the overrunning clutch 11 that it is separated in the forward direction and combined in the reverse direction, the pawl wheel 37 of the overrunning clutch 11 can only rotate in the forward direction relative to the sleeve 36, and the pawl wheel 37 is cut off under the action of the slide pin 38 when it moves in the reverse direction, that is, the pawl wheel 37 cannot rotate in the reverse direction, so that the helical sample 12 can only rotate in the forward direction under the action of the overrunning clutch 11 and cannot rotate in the reverse direction. Under the action of the helical sample 12 and the helical groove 7, when the piston 5 moves downward, the helical sample 12 cannot rotate in the reverse direction under the action of the overrunning clutch 11, and the helical sample 12 can drive the piston 5 to rotate through the helical groove 7 when the piston 5 moves downward, so that the piston 5 can drive the drill bit 4 to rotate through the self-lubricating connector 9, the splines 6 and the spline groove 10, so that the piston 5 can impact the drill bit 4 while driving the drill bit 4 to rotate; when the piston 5 moves upward, the piston 5 drives the helical sample 12 to rotate through the helical groove 7, and the helical sample 12 can rotate in the forward direction under the action of the overrunning clutch 11, so that the helical sample 12 idles, thereby reducing the load when the piston 5 moves upward, and further reducing the resistance when the piston 5 moves upward, so that the piston 5 can move upward quickly, thereby greatly reducing the time used when the piston 5 moves upward, effectively improving the impact frequency of the piston 5, and further improving the drilling efficiency.

[0033] The piston 5 above the overrunning clutch 11 is sequentially sleeved with a flange plate 39, a spacer sleeve 13, a spacer sleeve 14 and an inner cylinder 15 from bottom to top, and the flange plate 39 is fixedly connected with the outer shell 1; the top end surface of the sleeve 36 of the overrunning clutch 11 is provided with a pin 40, and the sleeve 36 is fixedly connected with the flange plate 39 through the pin 40, so that the sleeve 36 is prevented from rotating through the cooperation of the flange plate 39 and the pin 40. The spacer sleeve 13, the spacer sleeve 14 and the inner cylinder 15 are sealingly connected with the outer shell 1. The top end surface of the inner cylinder 15 is provided with a gas distribution valve 16, the gas distribution valve 16 is provided with a gas guide check ring 17, and a check valve is installed above the gas guide check ring 17 through a valve seat 18. The check valve comprises a valve rod 19, a valve head 20 and a return spring 21, the valve head 20 is movably inserted on the top end surface of the valve rod 19, and the return spring 21 is arranged between the valve head 20 and the valve rod 19; the valve rod 19 is threadedly connected with the valve seat 18; the valve head 20 above the valve rod 19 is slidingly and sealingly connected with the upper connector 2. The function of the check valve is to prevent backflow by sealing the flow channel of the upper connector 2 through the valve head 20 under the elastic force of the return spring 21, that is, only high-pressure gas can flow downward through the valve head 20, and cannot flow upward, thereby preventing impurities such as dust and debris from entering the inside, thereby ensuring that it is not easy to be blocked.

[0034] The gas guide check ring 17 is uniformly provided with flow-through holes 22, and the valve seat 18 around the valve rod 19 is uniformly provided with axial holes 23 in a circular ring shape, and the axial holes 23 are communicated with the annular space between the inner cylinder 15 and the outer shell 1 through the flow-through holes 22, so that the high-pressure gas entering from the upper connector 2 can enter the annular space between the inner cylinder 15 and the outer shell 1 through the axial holes 23 and the flow-through holes 22 in sequence, and then flow downward.

[0035] The piston 5 above the spline 6 is sequentially provided with an upper sealing flange 24, a middle sealing flange 25 and a lower sealing flange 26 from top to bottom, the upper sealing flange 24 and the middle sealing flange 25 are respectively slidingly and sealingly connected with the inner cylinder 15, and the lower sealing flange 26 is slidingly and sealingly connected with the spacer sleeve 14. The functions of the upper sealing flange 24, the middle sealing flange 25 and the lower sealing flange 26 are to form a seal through the upper sealing flange 24, the middle sealing flange 25 and the lower sealing flange 26, thereby forming a pressure difference, so that the piston 5 is driven to reciprocate under the driving of the pressure difference, thereby repeatedly impacting the drill bit 4 in the reciprocating process of the piston 5.

[0036] The piston 5 is provided with a piston center hole 27 penetrating the piston, the cross section of the gas distribution valve 16 is in the shape of “T”, and the center guide rod of the bottom of the gas distribution valve 16 is inserted and sealingly connected with the piston center hole 27. The function of the gas distribution valve 16 is to intermittently insert the guide rod of the gas distribution valve 16 into the piston center hole 27 to intermittently seal the piston center hole 27, thereby controlling the high-pressure gas flowing into the piston center hole 27 from the top end of the piston center hole 27, thereby controlling the flow of the high-pressure gas.

[0037] The inner cylinder 15 between the upper sealing flange 24 and the middle sealing flange 25 is provided with radial holes 28, which are respectively communicated with the annular space between the inner cylinder 15 and the outer shell 1 and the annular space between the piston 5 and the inner cylinder 15. The inner wall of the inner cylinder 15 above the radial holes 28 is provided with a gas distribution ring groove 41. The radial holes 28 are used to guide the high-pressure gas entering the annular space between the piston 5 and the inner cylinder 15 to flow between the upper sealing flange 24 and the middle sealing flange 25, so as to push the upper sealing flange 24 or the middle sealing flange 25 to move. When the high-pressure gas pushes the middle sealing flange 25 to move downward, the middle sealing flange 25 drives the piston 5 to move downward, so that the piston 5 performs a downstroke to impact the drill bit 4; when the high-pressure gas pushes the upper sealing flange 24 to move upward, the upper sealing flange 24 drives the piston 5 to move upward, so that the piston 5 performs an upstroke. Thus, the piston 5 repeatedly impacts the drill bit 4 in the alternating process of the downstroke and the upstroke.

[0038] The spacer sleeve 14 outside the lower sealing flange 26 is provided with a shoulder, and the shoulder is uniformly provided with spacer sleeve inner holes 29. The annular space between the piston 5 above the lower sealing flange 26 and the spacer sleeve 14 is communicated with the annular space between the piston 5 below the lower sealing flange 26 and the spacer sleeve 14 through the spacer sleeve inner holes 29. The piston 5 circumferentially between the lower sealing flange 26 and the spline 6 is uniformly provided with radial communication holes 30, which are respectively communicated with the piston central hole 27 and the annular space between the piston 5 below the lower sealing flange 26 and the spacer sleeve 14. The radial communication holes 30 are used to make the high-pressure gas sequentially pass through the spacer sleeve inner holes 29 and the radial communication holes 30 to enter the piston central hole 27 when the high-pressure gas flows downward through the annular space between the spacer sleeve 14 and the piston 5, so that the high-pressure gas continues to flow into the piston central hole 27 through the radial communication holes 30 when the top end of the piston central hole 27 is sealed by the gas distribution valve 16, and further ensures the uninterrupted flow of the high-pressure gas in the piston central hole 27. The lower sealing flange 26 is used to seal the spacer sleeve inner holes 29 through the lower sealing flange 26 when the piston performs a downstroke, so as to block the high-pressure gas from sequentially passing through the spacer sleeve inner holes 29 and the radial communication holes 30 to flow into the piston central hole 27, thereby making the high-pressure gas accumulate in the annular space outside the piston 5 above the lower sealing flange 26, and making the annular space outside the piston 5 above the lower sealing flange 26 build up pressure, so that the piston 5 is pushed to move upward by the high-pressure gas with gradually increasing pressure.

[0039] The drill bit 4 is provided with a drill bit center hole 31, a tail pipe 32 is threadedly mounted on the top end of the drill bit center hole 31, and the drill bit center hole 31 is communicated with the piston center hole 27 through the tail pipe 32; a plurality of exhaust holes 33 are connected to the bottom end of the drill bit center hole 31. Since the drill bit center hole 31 is communicated with the piston center hole 27, the high-pressure gas flowing in the piston center hole 27 can continue to flow downward in the drill bit center hole 31, and is discharged downward through the drill bit center hole 31, so that the high-pressure gas is used to blow the bottom of the drill bit. The exhaust holes 33 are used to guide the high-pressure gas to be discharged through the exhaust holes 33, so that the high-pressure gas is used to blow the bottom of the drill bit, the debris generated in the drilling process is blown away from the bottom of the drill bit 4, and then the debris is prevented from affecting the drilling of the drill bit.

[0040] The inner wall of the lower joint 3 is provided with an inner flange 34, and the drill bit 4 above the inner flange 34 is threadedly mounted with an anti-falling check ring 35. The inner flange 34 is used to block the anti-falling check ring 35 through the inner flange 34, so as to prevent the anti-falling check ring 35 from moving downward and being separated from the lower joint 3, thereby preventing the drill bit 4 connected with the anti-falling check ring 35 from moving downward and being separated from the lower joint 3, and protecting the drill bit 4 from falling into the well.

[0041] When the air hammer for drilling is working, the high-pressure gas entering the upper joint 2 overcomes the elastic force of the return spring 21 of the check valve to open the valve head 20 and enter the lower housing 1 below the upper joint 2. The high-pressure gas entering the lower housing 1 passes through the axial hole 23 of the valve seat 18, the flow-through hole 22 of the gas guide check ring 17, the annulus between the inner cylinder 15 and the outer housing 1, and the radial hole 28 on the inner cylinder 15 to enter between the piston 5 and the inner cylinder 15, and the high-pressure gas entering between the piston 5 and the inner cylinder 15 pushes the piston 5 to perform downward stroke and upward return. During the stroke of the piston 5, the overrunning clutch 11 drives the piston 5 to rotate through the spiral spline 12 cooperating with the spiral groove 7 on the piston 5, and the piston 5 rotates to drive the drill bit 4 to rotate through the spline 6, the spline groove 10 and the self-lubricating connector 9, so that the piston 5 can drive the drill bit 4 to rotate and drill in the process of impacting the drill bit 4, thereby improving the drilling efficiency. During the return of the piston 5, the piston 5 drives the spiral spline 12 to idle under the action of the overrunning clutch 11, so as to reduce the load of the return of the piston 5 and improve the speed of the return of the piston 5, thereby effectively improving the frequency of the reciprocating impact of the piston 5.

[0042] When the piston 5 is in the down stroke, the high pressure gas between the piston 5 and the inner cylinder 15 pushes the middle sealing flange 25 to move downward, and the middle sealing flange 25 drives the piston 5 to move downward. During the process that the high pressure gas pushes the middle sealing flange 25 to move downward, i.e. during the process that the piston 5 moves downward, the piston 5 drives the upper sealing flange 24 and the lower sealing flange 26 to move downward. During the process that the upper sealing flange 24 moves downward, the upper sealing flange 24 enters the gas distribution ring groove 41, and the high pressure gas enters the space above the piston 5 through the gas distribution ring groove 41, and the high pressure gas pushes the piston 5 to move downward by the top end surface of the piston 5 and the middle sealing flange 24. During the process that the piston 5 moves downward, the guide rod of the gas distribution valve 16 is gradually pulled out of the piston center hole 27 of the piston 5, and during the process that the guide rod of the gas distribution valve 16 is gradually pulled out, the guide rod of the gas distribution valve 16 gradually no longer seals the piston center hole 27, so that the high pressure gas can flow downward through the piston center hole 27. When the guide rod of the gas distribution valve 16 no longer seals the piston center hole 27 during the process that the piston 5 moves downward, the upper sealing flange 24 continues to move and starts to seal with the inner cylinder 15, and at the same time, the middle sealing flange 25 starts to separate from the inner wall of the inner cylinder 15, so that the high pressure gas can no longer push the piston to move downward by the top end surface of the piston 5 and the middle sealing flange 25. After the guide rod of the gas distribution valve 16 no longer seals the piston center hole 27 during the process that the piston 5 moves downward, the piston 5 continues to move downward under the action of its own inertia to perform the stroke and impact the drill bit 4, and the downward speed of the piston 5 decreases to 0. After the middle sealing flange 25 separates from the inner cylinder 15, the high pressure gas enters the annulus between the piston 5 and the spacer sleeve 14 through the radial hole 28. During the process that the downward speed of the piston 5 decreases to 0 during the down stroke, the lower sealing flange 26 moves downward to gradually block the flow passage between the spacer sleeve inner hole 29 on the spacer sleeve 14 and the radial communication hole 30 on the piston 5, so that the high pressure gas cannot enter the radial communication hole 30 from the spacer sleeve inner hole 29, thereby causing the high pressure air entering the annulus between the piston 5 and the spacer sleeve 14 to be pressurized in the annulus between the piston 5 and the spacer sleeve 14.

[0043] After the piston 5 downstroke speed is reduced to 0, the stroke is completed, and the piston 5 proceeds to return. After the piston 5 downstroke speed is reduced to 0, the high-pressure air in the annulus between the spacer sleeve 14 and the piston 5 pushes the upper sealing flange 24 sealed with the inner cylinder 15 to move upward, thereby pushing the piston 5 to move upward to return. After the piston 5 starts to return, the high-pressure gas at the top end of the piston 5 is pushed by the guide rod of the gas distribution valve 16 and the piston center hole 27 into the piston center hole 27. After the upper sealing flange 24 rises into the gas distribution ring groove 41, the high-pressure gas can no longer push the upper sealing flange 24 to move upward, that is, the piston 5 can no longer be pushed upward by the high-pressure gas, and the piston 5 continues to return upward under its own inertia. When the piston 5 returns, the piston 5 drives the middle sealing flange 25 and the lower sealing flange 26 to rise, respectively. At the same time, as the piston rises, the guide rod of the gas distribution valve 16 gradually inserts into the piston center hole 27, gradually sealing the top end of the piston center hole 27. During the rising of the middle sealing flange 25, the middle sealing flange 25 gradually seals with the inner cylinder 15, so that the high-pressure air is trapped in the annulus between the piston 5 above the middle sealing flange 25 and the inner cylinder 15. During the rising of the lower sealing flange 26, the lower sealing flange 26 gradually separates from the spacer sleeve inner hole 29, and no longer separates the communication between the spacer sleeve inner hole 29 and the radial communication hole 30. The high-pressure air in the annulus between the spacer sleeve 14 and the piston 5 flows downward into the piston center hole 27 through the spacer sleeve inner hole 29 and the radial communication hole 30 in sequence.

[0044] Because during the piston 5 stroke, the high-pressure gas enters the piston center hole 27 through the gap between the guide rod of the gas distribution valve 16 and the piston center hole 27; during the piston 5 return, the high-pressure gas enters the piston center hole 27 through the spacer sleeve inner hole 29 and the radial communication hole 30 in sequence; thus, the high-pressure gas in the piston center hole 27 can continuously flow downward, so that the high-pressure gas can continuously pass through the piston center hole 27, the tail pipe 32, the drill bit center hole 31 and the exhaust hole 33 to blow the drill bit 4 bottom, and at the same time, through the continuous blowing of the compressed air to the drill bit 4 bottom, the backflow is prevented, and the blockage caused by the backflow of the debris is avoided.

[0045] The air hammer for drilling can impact the drill bit 4 when the piston 5 moves downward, and can drive the drill bit 4 to rotate under the action of the overrunning clutch 11, so that the drill bit 4 can rotate and drill while impacting, thereby effectively improving the drilling efficiency. The overrunning clutch 11 can be idled when the piston 5 moves upward, reducing the load of the piston 5, so that the piston 5 can quickly return, thereby effectively increasing the impact frequency of the piston 5 and further improving the drilling efficiency. The problem of low drilling efficiency caused by the existing air hammer only impacting to drill is solved.

Claims

1. An air hammer for drilling, comprising an outer casing (1), an upper connector (2), a lower connector (3), a drill bit (4), and a piston (5), wherein the outer casing (1) is cylindrical, the upper connector (2) is threaded onto one end of the outer casing (1), and the drill bit (4) is movably mounted onto the other end of the outer casing (1) via the lower connector (3), and the piston (5) is disposed inside the outer casing (1) between the drill bit (4) and the upper connector (2); characterized in that: The top end of the drill bit (4) and the bottom end of the piston (5) are respectively provided with splines (6), and a helical groove (7) is arranged on the piston (5) between the splines (6); a self-lubricating connector (9) is movably arranged in the inner cylinder (8) in the outer shell (1) between the drill bit (4) and the piston (5), the self-lubricating connector (9) is provided with a spline groove (10), and the self-lubricating connector (9) is movably connected with the drill bit (4) and the piston (5) through the cooperation of the splines (6) and the spline groove (10); a overrunning clutch (11) is arranged in the outer shell (1) above the self-lubricating connector (9), and helical sample strips (12) are uniformly arranged on the inner wall of the overrunning clutch (11), and the helical sample strips (12) are slidably connected with the helical groove (7). The upper sealing flange (24), the middle sealing flange (25) and the lower sealing flange (26) are sequentially arranged on the piston (5) from top to bottom. During the piston stroke, the high-pressure gas pushes the middle sealing flange to move downward, and the piston drives the upper sealing flange and the lower sealing flange to move downward; during the downward movement of the upper sealing flange, the high-pressure gas enters above the piston, and the piston is pushed to move downward by the top end surface of the piston and the middle sealing flange; during the process that the downward stroke of the piston reduces to 0, the high-pressure gas is pressurized in the annulus between the spacer sleeve and the piston, and the high-pressure air pressurized in the annulus pushes the upper sealing flange to move upward, thereby pushing the piston to move upward for return.

2. An air hammer for use in drilling a well bore according to claim 1 wherein: The flange plate (39), the spacer sleeve retainer ring (13), the spacer sleeve (14) and the inner cylinder (15) are sequentially sleeved on the piston (5) above the overrunning clutch (11) from bottom to top, a gas distribution valve (16) is arranged on the top end surface of the inner cylinder (15), a gas guide retainer ring (17) is arranged on the gas distribution valve (16), and a check valve is arranged on the gas guide retainer ring (17) through a valve seat (18).

3. An air hammer for use in drilling a well bore according to claim 2 wherein: The check valve comprises a valve rod (19), a valve head (20) and a reset spring (21), the valve head (20) is movably inserted on the top end surface of the valve rod (19), and the reset spring (21) is arranged between the valve head (20) and the valve rod (19); the valve rod (19) is threadedly connected with the valve seat (18); the valve head (20) above the valve rod (19) is slidably and sealingly connected with the upper connector (2).

4. An air hammer for use in drilling a well bore according to claim 2 wherein: The gas guide retainer ring (17) is uniformly provided with flow-through holes (22), and the valve seat (18) around the valve rod (19) is uniformly provided with axial holes (23) in the form of a circular ring, and the axial holes (23) are communicated with the annulus between the inner cylinder (15) and the outer shell (1) through the flow-through holes (22).

5. An air hammer for use in drilling a well bore according to claim 1 wherein: The upper sealing flange (24) and the middle sealing flange (25) are respectively slidably and sealingly connected with the inner cylinder (15), and the lower sealing flange (26) is slidably and sealingly connected with the spacer sleeve (14).

6. An air hammer for use in drilling a well bore according to claim 5 wherein: The piston (5) is provided with a piston center hole (27) penetrating the piston, the cross section of the gas distribution valve (16) is in the shape of "T", and the guide rod at the bottom center of the gas distribution valve (16) is sealingly connected with the piston center hole (27) by insertion.

7. An air hammer for use in drilling a well bore according to claim 5 wherein: The inner cylinder (15) between the upper sealing flange (24) and the middle sealing flange (25) is provided with a radial hole (28) which is communicated with the annulus between the inner cylinder (15) and the outer shell (1) and the annulus between the piston (5) and the inner cylinder (15) respectively; the inner wall of the inner cylinder (15) above the radial hole (28) is provided with a gas distribution ring groove (41).

8. An air hammer for use in drilling a well bore according to claim 5 wherein: The spacer sleeve (14) outside the lower sealing flange (26) is provided with a shoulder which is uniformly provided with a spacer sleeve inner hole (29); the annulus between the piston (5) above the lower sealing flange (26) and the spacer sleeve (14) is communicated with the annulus between the piston (5) below the lower sealing flange (26) and the spacer sleeve (14) through the spacer sleeve inner hole (29).

9. An air hammer for use in drilling a well bore according to claim 6 wherein: The piston (5) between the lower sealing flange (26) and the spline (6) is uniformly provided with a radial communication hole (30) which is communicated with the piston central hole (27) and the annulus between the piston (5) below the lower sealing flange (26) and the spacer sleeve (14) respectively.

10. An air hammer for use in drilling a well bore according to claim 6 wherein: The drill bit (4) is provided with a drill bit central hole (31) which is threadedly installed with a tail pipe (32) at the top end; the drill bit central hole (31) is communicated with the piston central hole (27) through the tail pipe (32); the bottom end of the drill bit central hole (31) is connected with a plurality of exhaust holes (33); the inner wall of the lower joint (3) is provided with an inner flange (34); the drill bit (4) above the inner flange (34) is threadedly installed with an anti-falling check ring (35).

Images