Hydraulic valve group and system for controlling power head to axially float along with threads

Abstract

The utility model discloses a hydraulic valve group and system for controlling a power head to axially float along with threads, and relates to the technical field of hydraulic control, two oil inlets of a shuttle valve are arranged close to a third oil port and a fourth oil port and are respectively communicated with a first oil way and a second oil way, a port I of a two-position three-way manual valve is communicated with an oil drainage port, and a port II of the two-position three-way manual valve is communicated with an oil drainage port. When the two-position three-way manual valve keeps the spring position, a first port and a second port of the two-position three-way manual valve are communicated, pilot ports of the two hydraulic control one-way valve sets are connected in parallel and return oil through the first port of the two-position three-way manual valve, the two hydraulic control one-way valve sets are closed, and the two hydraulic control one-way valve sets return oil through the second port of the two-position three-way manual valve. When the two-position three-way manual valve is switched to the locking position, the third port and the second port of the two-position three-way manual valve are communicated, the pilot ports of the two hydraulic control one-way valve sets are both communicated with the second port of the two-position three-way manual valve, and the two hydraulic control one-way valve sets are opened. The service life of the power head main shaft and the drill rod can be prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic control, in particular to a hydraulic valve group and a system for controlling the axial floating of a power head along with a thread. Background Art

[0002] When adding or removing drill pipes with a power head drill, it is necessary to screw on and off the threads between the main shaft and the drill pipe, as well as between the drill pipes through the power head. During this process, the power head drives the main shaft to rotate forward and screw into or rotate backward and screw out the threads of the drill pipe, and at this time, the power head needs to move axially. The traditional operation method usually manually controls the axial movement of the power head, so that the main shaft and the drill pipe move axially along with the screwing in and out of the threads. However, this method of manually controlling the axial movement of the power head is difficult to control the speed and position of the thread engagement, often causing serious damage to the threads, and greatly shortening the service life of the drill pipe and the main shaft of the power head. Summary of the Utility Model

[0003] The purpose of the utility model is to provide a hydraulic valve group and a system for controlling the axial floating of a power head along with a thread, so as to solve the problems existing in the above-mentioned prior art and extend the service life of the main shaft of the power head and the drill pipe.

[0004] To achieve the above purpose, the utility model provides the following scheme:

[0005] The utility model provides a hydraulic valve group for controlling the axial floating of a power head along with a thread, which includes a valve block, and a shuttle valve, a two-position three-way manual valve and two groups of pilot-operated check valve groups installed on the valve block. The valve block is provided with an oil drain port, a first oil port for communicating with the large chamber of the power head oil cylinder, a second oil port for communicating with the small chamber of the power head oil cylinder, and a third oil port and a fourth oil port for connecting a slewing motor, and both the third oil port and the fourth oil port can communicate with the slewing union of a multi-way valve. The first group of pilot-operated check valve groups is located on a first oil path between the first oil port and the third oil port, and the second group of pilot-operated check valve groups is located on a second oil path between the second oil port and the fourth oil port. Two oil inlets of the shuttle valve are arranged close to the third oil port and the fourth oil port, and the two oil inlets of the shuttle valve are respectively communicated with the first oil path and the second oil path. Port 1 of the two-position three-way manual valve is communicated with the oil drain port, and the oil outlet of the shuttle valve is communicated with Port 3 of the two-position three-way manual valve. When the two-position three-way manual valve is in the spring position, Port 1 and Port 2 of the two-position three-way manual valve are communicated, and the pilot ports of the two groups of pilot-operated check valve groups are connected in parallel and return oil through Port 1 of the two-position three-way manual valve, and the two groups of pilot-operated check valve groups are closed. When the two-position three-way manual valve is switched to the locking position, Port 3 and Port 2 of the two-position three-way manual valve are communicated, and the pilot ports of the two groups of pilot-operated check valve groups are both communicated with Port 2 of the two-position three-way manual valve, and the two groups of pilot-operated check valve groups are opened.

[0006] Preferably, the first set of hydraulic check valve groups includes a first hydraulic check valve and a second hydraulic check valve connected in series along the first oil path. One port of the first hydraulic check valve communicates with the first oil port, port two of the first hydraulic check valve communicates with port two of the second hydraulic check valve, and port one of the second hydraulic check valve communicates with the third oil port.

[0007] Preferably, the second set of hydraulic check valve groups includes a third hydraulic check valve and a fourth hydraulic check valve connected in series along the second oil path. One port of the third hydraulic check valve communicates with the second oil port, port two of the third hydraulic check valve communicates with port two of the fourth hydraulic check valve, and port one of the fourth hydraulic check valve communicates with the fourth oil port.

[0008] Preferably, it further includes two first one-way valves and two pressure reducing valves. The two pressure reducing valves are respectively installed on the first oil path and the second oil path. The pressure reducing valve on the first oil path is located between the first hydraulic check valve and the second hydraulic check valve, and the pressure reducing valve on the second oil path is located between the third hydraulic check valve and the fourth hydraulic check valve; the two first one-way valves and the two pressure reducing valves correspond one by one, and the first one-way valve is arranged in parallel with the pressure reducing valve.

[0009] The present utility model also provides a hydraulic system for controlling the axial floating of the power head along the thread, which includes a power head oil cylinder, a multi-way valve, and the hydraulic valve group for controlling the axial floating of the power head along the thread according to any one of the above technical solutions. The large chamber and the small chamber of the power head oil cylinder are both connected to the oil cylinder connection of the multi-way valve, both ends of the rotary motor are connected to the rotary connection of the multi-way valve, and the large chamber of the power head oil cylinder communicates with the first oil port, the small chamber of the power head oil cylinder communicates with the second oil port, and both ends of the rotary motor communicate with the third oil port and the fourth oil port respectively.

[0010] Preferably, when the drill pipe thread is connected by the forward rotation of the rotary motor, high-pressure oil enters the second oil path through the fourth oil port, enters the small chamber of the power head oil cylinder through the second oil port, and the oil returns and is led out from the large chamber of the power head oil cylinder and then enters the first oil path through the first oil port, and enters the return oil path of the multi-way valve through the third oil port.

[0011] Preferably, when the drill pipe thread is unscrewed by the reverse rotation of the rotary motor, high-pressure oil enters the first oil path through the third oil port, enters the large chamber of the power head oil cylinder through the first oil port, and the oil returns and is led out from the small chamber of the power head oil cylinder and then enters the second oil path through the second oil port, and enters the return oil path of the multi-way valve through the fourth oil port.

[0012] The present utility model has achieved the following technical effects compared with the prior art:

[0013] For the hydraulic valve group and system provided by the present utility model for controlling the axial floating of the power head along the thread, when the two-way three-position manual valve maintains the spring position, port one and port two of the two-way three-position manual valve are connected, and the pilot ports of the two groups of pilot-operated check valve groups are connected in parallel and return oil through port one of the two-way three-position manual valve. The two groups of pilot-operated check valve groups are closed, and at this time, the first oil port, the second oil port, the third oil port, and the fourth oil port are completely locked and not connected to each other. The slewing motor and the power head oil cylinder are two independent circuits, so that when operating the slewing joint or the oil cylinder joint of the multi-way valve, they will not affect each other. When the two-way three-position manual valve is switched to the locking position, port three and port two of the two-way three-position manual valve are connected, and the pilot ports of the two groups of pilot-operated check valve groups are both connected to port two of the two-way three-position manual valve, and the two groups of pilot-operated check valve groups are opened. Thus, when it is not necessary to realize the axial floating function of the power head for screwing and unscrewing the drill pipe along the thread, as long as the knob of the two-way three-position manual valve is kept in the reset state. When it is necessary to realize the axial following function of the power head for screwing and unscrewing the drill pipe, as long as the knob of the two-way three-position manual valve is rotated to the locking position, this function can be automatically realized. By hydraulic control, the problem of damage to the thread when the power head screws and unscrews along with the main shaft and the drill pipe is solved, without any mechanical assistance, and the operation is simple and convenient. At the same time, since the hydraulic system control is at the millisecond level, the axial floating of the power head when screwing and unscrewing the thread of the main shaft and the drill pipe can be controlled more sensitively to better protect the thread and extend the service life of the power head main shaft and the drill pipe. Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 It is the bottom view of the hydraulic valve group for controlling the axial floating of the power head along the thread in Embodiment 1;

[0016] Figure 2 It is the top view of the hydraulic valve group for controlling the axial floating of the power head along the thread in Embodiment 1;

[0017] Figure 3 It is the side view of the hydraulic valve group for controlling the axial floating of the power head along the thread in Embodiment 1;

[0018] Figure 4 It is the hydraulic control schematic diagram of the hydraulic system for controlling the axial floating of the power head along the thread in Embodiment 2;

[0019] In the figure: 1 - valve block, 11 - first oil port, 12 - second oil port, 13 - third oil port, 14 - fourth oil port, 15 - oil drain port, 2 - pilot-operated check valve group, 21 - first pilot-operated check valve, 22 - second pilot-operated check valve, 23 - third pilot-operated check valve, 24 - fourth pilot-operated check valve, 3 - shuttle valve, 4 - two-position three-way manual valve, 5 - pressure reducing valve, 6 - first check valve, 7 - multi-way valve, 71 - slewing connection, 72 - cylinder connection, 8 - power head cylinder, 81 - large chamber, 82 - small chamber, 9 - slewing motor. Detailed implementation mode

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] The purpose of the present invention is to provide a hydraulic valve group and system for controlling the axial floating of the power head along the thread, so as to solve the problems existing in the prior art and extend the service life of the main shaft of the power head and the drill pipe.

[0022] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation modes.

[0023] Embodiment 1

[0024] As Figures 1 - 4As shown in the figure, this embodiment provides a hydraulic valve group for controlling the axial floating of the power head along the thread, which includes a valve block 1, a shuttle valve 3, a two-position three-way manual valve 4 and two groups of pilot-operated check valve groups 2 installed on the valve block 1. The valve block 1 is a high-pressure valve block with multiple oil circuits inside. The high-pressure valve block is processed from 45 steel after heat treatment and formed by surface nickel plating or QPQ treatment. The valve block 1 is provided with an oil drain port 15, a first oil port 11 for connecting the large chamber 81 of the power head oil cylinder 8, a second oil port 12 for connecting the small chamber 82 of the power head oil cylinder 8, and a third oil port 13 and a fourth oil port 14 for connecting the rotary motor 9. The third oil port 13 and the fourth oil port 14 are in parallel with the working oil ports of the rotary motor 9 in the hydraulic drill. The first oil port 11, the second oil port 12 and the oil ports of the large chamber 81 and the small chamber 82 of the power head oil cylinder 8 in the hydraulic drill are in parallel. Both the third oil port 13 and the fourth oil port 14 can be connected to the rotary connection of the multi-way valve 7. The first group of pilot-operated check valve groups 2 is located on the first oil circuit between the first oil port 11 and the third oil port 13. The second group of pilot-operated check valve groups 2 is located on the second oil circuit between the second oil port 12 and the fourth oil port 14. The two inlet ports of the shuttle valve 3 are arranged close to the third oil port 13 and the fourth oil port 14. The two inlet ports of the shuttle valve 3 are respectively connected to the first oil circuit and the second oil circuit. The port 1 of the two-position three-way manual valve 4 is connected to the oil drain port 15. The outlet port of the shuttle valve 3 is connected to the port 3 of the two-position three-way manual valve 4. When the two-position three-way manual valve 4 is in the spring position, the port 1 and the port 2 of the two-position three-way manual valve 4 are connected, and the pilot ports of the two groups of pilot-operated check valve groups 2 are in parallel and return oil through the port 1 of the two-position three-way manual valve 4. The two groups of pilot-operated check valve groups 2 are closed, and at this time, the first oil port 11, the second oil port 12, the third oil port 13 and the fourth oil port 14 are completely locked and do not communicate with each other. The rotary motor 9 and the power head oil cylinder 8 are two independent circuits, so that when operating the rotary connection 71 or the cylinder connection 72 of the multi-way valve 7, they will not affect each other. When the two-position three-way manual valve 4 is switched to the locked position, the port 3 and the port 2 of the two-position three-way manual valve 4 are connected, and the pilot ports of the two groups of pilot-operated check valve groups 2 are both connected to the port 2 of the two-position three-way manual valve 4. The two groups of pilot-operated check valve groups 2 are opened. Thus, when it is not necessary to realize the function of the power head floating axially along the thread during the screwing and unscrewing of the drill pipe, as long as the knob of the two-position three-way manual valve 4 is kept in the reset state. When it is necessary to realize the function of the power head following axially during the screwing and unscrewing of the drill pipe, as long as the knob of the two-position three-way manual valve 4 is rotated to the locked position, this function can be automatically realized. By hydraulic control, the problem of damage to the thread when the power head screws and unscrews along with the main shaft and the drill pipe is solved, without any mechanical assistance, and the operation is simple and convenient. At the same time, since the hydraulic system control is at the millisecond level, the axial floating of the power head during the screwing and unscrewing of the main shaft and the drill pipe thread can be controlled more sensitively to better protect the thread and extend the service life of the power head main shaft and the drill pipe.

[0025] Specifically, the first set of pilot-operated check valve group 2 includes a first pilot-operated check valve 21 and a second pilot-operated check valve 22 arranged in series along the first oil circuit. Port one of the first pilot-operated check valve 21 is connected to the first oil port 11, port two of the first pilot-operated check valve 21 is connected to port two of the second pilot-operated check valve 22, and port one of the second pilot-operated check valve 22 is connected to the third oil port 13, thus facilitating the conduction of the first oil circuit.

[0026] The second set of pilot-operated check valve group 2 includes a third pilot-operated check valve 23 and a fourth pilot-operated check valve 24 arranged in series along the second oil circuit. Port one of the third pilot-operated check valve 23 is connected to the second oil port 12, port two of the third pilot-operated check valve 23 is connected to port two of the fourth pilot-operated check valve 24, and port one of the fourth pilot-operated check valve 24 is connected to the fourth oil port 14, thus facilitating the conduction of the second oil circuit.

[0027] The pilot oil source of the above four pilot-operated check valves is controlled by a two-position three-way manual valve 4 in one key to achieve manual one-key control of the opening or closing of the hydraulic valve group.

[0028] This embodiment further includes two first check valves 6 and two pressure reducing valves 5. The two pressure reducing valves 5 are respectively installed on the first oil circuit and the second oil circuit. The pressure reducing valve 5 on the first oil circuit is located between the first pilot-operated check valve 21 and the second pilot-operated check valve 22, and the pressure reducing valve 5 on the second oil circuit is located between the third pilot-operated check valve 23 and the fourth pilot-operated check valve 24; the two first check valves 6 and the two pressure reducing valves 5 correspond one by one, and the first check valve 6 is arranged in parallel with the pressure reducing valve 5. Through the setting of the pressure reducing valve 5, the maximum pressure when the power head cylinder 8 floats with the thread can be limited to better protect the threads of the drill pipe and the power head main shaft.

[0029] The hydraulic valve group provided in this embodiment for controlling the axial floating of the power head with the thread can be directly added to the hydraulic system of all hydraulic power head drilling rigs without changing the original machine system, and has good adaptability.

[0030] Embodiment Two

[0031] As Figures 1 - 4 shown, this embodiment provides a hydraulic system for controlling the axial floating of the power head with the thread, including a power head cylinder 8, a multi-way valve 7, and the hydraulic valve group for controlling the axial floating of the power head with the thread in Embodiment One. Both the large chamber 81 and the small chamber 82 of the power head cylinder 8 are connected to the cylinder connection of the multi-way valve 7, both ends of the slewing motor 9 are connected to the slewing connection of the multi-way valve 7, and the large chamber 81 of the power head cylinder 8 is connected to the first oil port 11, the small chamber 82 of the power head cylinder 8 is connected to the second oil port 12, and both ends of the slewing motor 9 are respectively connected to the third oil port 13 and the fourth oil port 14. Among them, the specific connection method between the power head cylinder 8 and the multi-way valve 7 is the same as that in the prior art.

[0032] Specifically, when the drill pipe thread connected to the rotary motor 9 rotates forward, high-pressure oil enters the second oil circuit through the fourth oil port 14, and enters the small chamber 82 of the power head cylinder 8 through the second oil port 12. The oil returns and is led out from the large chamber 81 of the power head cylinder 8, then enters the first oil circuit through the first oil port 11, and enters the return oil circuit of the multi-way valve 7 through the third oil port 13, promoting the power head to axially move along the drill pipe, and compensating for the screwed-in thread distance while the power head rotates forward.

[0033] When the drill pipe thread connected to the rotary motor 9 rotates reversely to unscrew, high-pressure oil enters the first oil circuit through the third oil port 13, and enters the large chamber 81 of the power head cylinder 8 through the first oil port 11. The oil returns and is led out from the small chamber 82 of the power head cylinder 8, then enters the second oil circuit through the second oil port 12, and enters the return oil circuit of the multi-way valve 7 through the fourth oil port 14, promoting the power head to axially move away from the drill pipe, and compensating for the unscrewed thread distance while the power head rotates reversely.

[0034] Embodiment III

[0035] As Figures 1 - 4 shown, this embodiment provides a method for controlling the axial floating of the power head along with the thread, using the hydraulic system for controlling the axial floating of the power head along with the thread in Embodiment II, including the following situations:

[0036] When the power head is in the non-thread-unscrewing and non-threading working condition, the two-way three-position manual valve 4 remains in the spring position. At this time, port two and port one of the two-way three-position manual valve 4 are communicated. The pilot ports of the four pilot-operated check valves are connected in parallel and return oil through port one of the two-way three-position manual valve 4, so as to realize that all four pilot-operated check valves are in the closed state, ensuring that the first oil port 11, the second oil port 12, the third oil port 13 and the fourth oil port 14 are completely locked and not communicated with each other. At this time, the rotary motor 9 and the power head cylinder 8 are two independent circuits, and operating the rotary connection 71 or the cylinder connection 72 of the multi-way valve 7 will not affect each other;

[0037] When it is necessary to unscrew or screw the drill pipe thread with the power head, manually switch the two-way three-position manual valve 4 to the locked position. At this time, among the third oil port 13 and the fourth oil port 14, the side with higher pressure enters port three of the two-way three-position manual valve 4 through one of the oil inlets of the shuttle valve 3, and enters port two through port three of the two-way three-position manual valve 4. Port two of the two-way three-position manual valve 4 is respectively communicated with the pilot ports of the four pilot-operated check valves, so that all four pilot-operated check valves are opened:

[0038] At this time, if the rotary motor 9 is operated to rotate the drill pipe thread in the forward direction, the high-pressure oil enters the fourth oil port 14, port one of the fourth pilot-operated check valve 24, port two of the fourth pilot-operated check valve 24, port two of the pressure reducing valve 5, port one of the pressure reducing valve 5, port two of the third pilot-operated check valve 23, port one of the third pilot-operated check valve 23 in sequence, and finally enters the small chamber 82 of the power head cylinder 8 through the second oil port 12; the oil return enters the first oil port 11, port one of the first pilot-operated check valve 21, port two of the first pilot-operated check valve 21, port two of the first check valve 6, port one of the first check valve 6, port two of the second pilot-operated check valve 22, port one of the second pilot-operated check valve 22 in sequence from the large chamber 81 of the power head cylinder 8, and finally enters the oil return circuit of the multi-way valve 7 through the third oil port 13, prompting the power head to axially move towards the drill pipe, compensating for the screwed-in thread distance while the power head rotates forward;

[0039] At this time, if the rotary motor 9 is operated to unscrew the drill pipe thread in the reverse direction, the internal oil circuit circulation process in the valve block 1 is opposite to the working condition of the drill pipe thread being rotated forward by the rotary motor 9, and the high-pressure oil enters the first oil circuit from the third oil port 13 and enters the large chamber 81 of the power head cylinder 8 through the first oil port 11, and the oil return enters the second oil circuit from the second oil port 12 and enters the oil return circuit of the multi-way valve 7 through the fourth oil port 14, so as to prompt the power head to axially move away from the drill pipe, compensating for the unscrewed thread distance while the power head rotates in the reverse direction. In the above process, the pressure reducing valve 5 limits the maximum pressure when the power head cylinder 8 floats with the thread, so as to better protect the threads of the drill pipe and the power head spindle.

[0040] In the present utility model, specific examples are used to elaborate on the principle and implementation manner of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present utility model.

Claims

1. A hydraulic valve group for controlling the axial floating of a power head along the thread, characterized in that: It includes a valve block, as well as a shuttle valve, a two-position three-way manual valve and two groups of pilot-operated check valve groups installed on the valve block. An oil drain port, a first oil port for connecting the large chamber of the power head cylinder, a second oil port for connecting the small chamber of the power head cylinder, a third oil port and a fourth oil port for connecting the slewing motor are opened on the valve block. The third oil port and the fourth oil port can both be connected to the slewing union of the multi-way valve. The first group of pilot-operated check valve groups is located on the first oil path between the first oil port and the third oil port. The second group of pilot-operated check valve groups is located on the second oil path between the second oil port and the fourth oil port. Two inlet ports of the shuttle valve are arranged close to the third oil port and the fourth oil port. The two inlet ports of the shuttle valve are respectively connected to the first oil path and the second oil path. Port 1 of the two-position three-way manual valve is connected to the oil drain port. The outlet port of the shuttle valve is connected to Port 3 of the two-position three-way manual valve. When the two-position three-way manual valve is in the holding spring position, Port 1 and Port 2 of the two-position three-way manual valve are connected, and the pilot ports of the two groups of pilot-operated check valve groups are in parallel and return oil through Port 1 of the two-position three-way manual valve. The two groups of pilot-operated check valve groups are closed. When the two-position three-way manual valve is switched to the locking position, Port 3 and Port 2 of the two-position three-way manual valve are connected, and the pilot ports of the two groups of pilot-operated check valve groups are both connected to Port 2 of the two-position three-way manual valve. The two groups of pilot-operated check valve groups are opened.

2. The hydraulic valve group for controlling the axial floating of the power head along the thread according to claim 1, wherein: The first group of pilot-operated check valve groups includes a first pilot-operated check valve and a second pilot-operated check valve connected in series along the first oil path. Port 1 of the first pilot-operated check valve is connected to the first oil port. Port 2 of the first pilot-operated check valve is connected to Port 2 of the second pilot-operated check valve. Port 1 of the second pilot-operated check valve is connected to the third oil port.

3. The hydraulic valve group for controlling the axial floating of the power head along the thread according to claim 2, wherein: The second group of pilot-operated check valve groups includes a third pilot-operated check valve and a fourth pilot-operated check valve connected in series along the second oil path. Port 1 of the third pilot-operated check valve is connected to the second oil port. Port 2 of the third pilot-operated check valve is connected to Port 2 of the fourth pilot-operated check valve. Port 1 of the fourth pilot-operated check valve is connected to the fourth oil port.

4. The hydraulic valve set for controlling the axial floating of the power head along the thread according to claim 3, characterized in that: It also includes two first one-way valves and two pressure reducing valves. The two pressure reducing valves are respectively installed on the first oil path and the second oil path. The pressure reducing valve on the first oil path is located between the first pilot-operated check valve and the second pilot-operated check valve. The pressure reducing valve on the second oil path is located between the third pilot-operated check valve and the fourth pilot-operated check valve. The two first one-way valves and the two pressure reducing valves are in one-to-one correspondence, and the first one-way valve is arranged in parallel with the pressure reducing valve.

5. A hydraulic system for controlling the axial floating of a power head along the thread, characterized in that: It includes a power head oil cylinder, a multi-way valve, and a hydraulic valve group for controlling the axial floating of the power head along the thread as described in any one of claims 1-4. The large chamber and the small chamber of the power head oil cylinder are both connected to the oil cylinder connection of the multi-way valve. Both ends of the rotary motor are connected to the rotary connection of the multi-way valve. Moreover, the large chamber of the power head oil cylinder is connected to the first oil port, the small chamber of the power head oil cylinder is connected to the second oil port, and both ends of the rotary motor are respectively connected to the third oil port and the fourth oil port.

6. The hydraulic system for controlling the axial floating of the power head along the thread according to claim 5, wherein: When the rotary motor rotates forward to connect the drill pipe thread, high-pressure oil enters the second oil circuit through the fourth oil port, enters the small chamber of the power head oil cylinder through the second oil port, and the oil returns from the large chamber of the power head oil cylinder, then enters the first oil circuit through the first oil port, and enters the return oil circuit of the multi-way valve through the third oil port.

7. The hydraulic system for controlling the axial floating of the power head along the thread according to claim 5, wherein: When the rotary motor rotates reversely to unscrew the drill pipe thread, high-pressure oil enters the first oil circuit through the third oil port, enters the large chamber of the power head oil cylinder through the first oil port, and the oil returns from the small chamber of the power head oil cylinder, then enters the second oil circuit through the second oil port, and enters the return oil circuit of the multi-way valve through the fourth oil port.

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