An open-type power tong main tong and its control method without tooth marks

Abstract

The present invention relates to an open-type toothless power tong main tong and its control method, which includes a hydraulic cylinder lever clamping type tong head and a hydraulic control system. It is characterized in that the hydraulic cylinder lever clamping type tong head includes a lever clamping mechanism driven by a hydraulic cylinder, and the hydraulic control system includes a manual reversing combination valve, a quick-connect combination assembly, a pressure relief device and a shunt pressure maintaining device. The present invention adopts a lever clamping mechanism driven by a hydraulic cylinder to provide greater clamping force, with a compact structure and reliable clamping; adopts a pluggable oil supply and return system and a pressure relief device with an accumulator to meet the rotating oil supply and return needs of the tong head clamping mechanism; adopts multi-faceted safety guarantee measures to ensure the safety and reliability of the operation; at the same time, the tooth plate is increased in height and size to increase the friction area; further selects wear-resistant non-metallic materials to increase the friction force to achieve sufficient torque and realize toothless operation of special pipes, with stable operation, safety and reliability, and huge economic and social benefits.

Description

Technical Field

[0001] The present invention relates to a power tong for oilfield pipes, in particular to an open-type power tong main tong for non-tooth-mark operation of oilfield pipe strings and its control method, belonging to the technical field of design and manufacturing of oil equipment. Background Art

[0002] Generally, power tongs are generally divided into a main tong and a back tong. The back tong clamps the lower part of the pipe string and does not rotate, and the main tong clamps the upper part of the pipe string and rotates to perform the make-up or break-out operation. In recent years, with the development of oil extraction technology, a large number of special pipes such as stainless steel and fiberglass tubing, casing pipes, and drill pipes have been used. Since tooth marks are not allowed on the surface of special pipes and clamping slippage is not allowed to damage the surface, and at the same time, a relatively large make-up or break-out torque is required, this brings difficulties to non-tooth-mark clamping. The prior art generally adopts a roller climbing clamping structure, the tooth plate is made of a non-metallic wear-resistant material, and a large inclusion angle is adopted to increase the friction force to meet the general operation requirements. However, during the operation process, the clamping is very unstable, and clamping slippage often occurs, damaging the surface layer of the special pipe, and a larger torque cannot be achieved. Therefore, for the make-up and break-out operations of special pipes, new structures and operation procedures are needed. Summary of the Invention

[0003] The present invention provides an open-type non-tooth-mark power tong main tong and its control method, which uses a lever clamping mechanism driven by a hydraulic cylinder to provide stable clamping force, uses a pluggable oil supply and return system to meet the rotation of the clamping mechanism of the tong head, and sets up a multi-directional safety protection mechanism to achieve the purpose of non-tooth-mark safe operation of special pipes.

[0004] To achieve the above object, the present invention is implemented by the following technical solutions: An open-type toothless power tong main tong, comprising a hydraulic cylinder lever clamping type tong head, a housing, a safety door, a power transmission system and a hydraulic control system. The power transmission system is arranged at the rear of the housing, and the safety door is arranged at the front opening of the housing. The power transmission system comprises a hydraulic motor and a transmission gear, and the hydraulic motor transmits power to the hydraulic cylinder lever clamping type tong head through the transmission gear. The hydraulic cylinder lever clamping type tong head is arranged at the front of the housing and comprises a tong head opening large gear, a single-rod hydraulic cylinder, a clamping arm, a rotating shaft, a front jaw plate assembly, a pin, a rear jaw plate assembly and a limiting block. The single-rod hydraulic cylinder, the clamping arm, the rotating shaft and the pin form a group of hydraulic cylinder-driven lever clamping mechanisms, and there are two groups of the hydraulic cylinder-driven lever clamping mechanisms. The two groups of hydraulic cylinder-driven lever clamping mechanisms are arranged in the inner cavity of the tong head opening large gear and are symmetrically arranged along the axis A-A symmetrical to the opening of the tong head opening large gear. The single-rod hydraulic cylinder is fastened to the tong head opening large gear. The clamping arm forms a fixed hinge rotating pair with the tong head opening large gear through the rotating shaft. The single-rod hydraulic cylinder comprises a single-rod head, and the single-rod head abuts against one end of the clamping arm, and a pin is arranged at the other end of the clamping arm. The front jaw plate assembly is strung on the pin to form a movable hinge of a rotating pair, and it comprises a front jaw plate and an arc-shaped tooth plate.

[0005] The rear jaw plate assembly comprises a rear jaw plate and an arc-shaped tooth plate. The central plane D-D thereof coincides with the cross-section of the axis A-A symmetrical to the opening of the tong head opening large gear. The back of it fits and is fastened to the inner arc of the tong head opening large gear. The two sides of the rear jaw plate assembly are limited by limiting blocks, and the limiting blocks are fixed integrally with the tong head opening large gear.

[0006] The hydraulic control system comprises a manual reversing combination valve, a quick-connect combination assembly, a pressure relief device and a flow splitting and pressure maintaining device. The manual reversing combination valve comprises a first manual reversing valve and a second manual reversing valve. The quick-connect combination assembly comprises a male combination joint, a female combination joint and a wrench. The manual reversing combination valve and the female combination joint are arranged on the housing. The flow splitting and pressure maintaining device, the pressure relief device and the male combination joint are arranged on the hydraulic cylinder lever clamping type tong head.

[0007] The first manual reversing valve is connected to the oil port of the hydraulic motor to form a hydraulic motor control circuit, which controls the forward and reverse rotation of the hydraulic motor and drives the hydraulic cylinder lever clamping type tong head to rotate. When the first manual reversing valve is pushed, the hydraulic cylinder lever clamping type tong head rotates in the make-up direction. When the first manual reversing valve is pulled, the hydraulic cylinder lever clamping type tong head rotates in the break-out direction.

[0008] The second manual reversing valve is connected to the single-rod hydraulic cylinder through a quick-connect combination assembly and a flow-dividing pressure-holding device to form a control circuit for the single-rod hydraulic cylinder; the flow-dividing pressure-holding device is arranged between one oil port of the second manual reversing valve and the rodless cavity of the single-rod hydraulic cylinder, and it consists of a flow-dividing valve and a pilot-operated check valve. The inlet port of the pilot-operated check valve is connected to the male combination joint connecting one oil port of the second manual reversing valve, the flow direction of its pilot-operated check valve points to the single-rod hydraulic cylinder, its outlet port is connected to the inlet port of the flow-dividing valve, its pilot port is connected to the male combination joint connecting the other oil port of the second manual reversing valve, and the two outlet ports of the flow-dividing valve are respectively connected to the rodless cavities of two single-rod hydraulic cylinders; the other oil port of the second manual reversing valve is connected to the rod cavity of the single-rod hydraulic cylinder through a quick-connect combination assembly; when the second manual reversing valve is pushed, the hydraulic oil flows through the flow-dividing pressure-holding device to the rodless cavity of the single-rod hydraulic cylinder, and the single-rod hydraulic cylinder extends; when the second manual reversing valve is pulled, the hydraulic oil flows to the rod cavity of the single-rod hydraulic cylinder, and the single-rod hydraulic cylinder retracts;

[0009] The pressure relief device is arranged in the oil circuit between one oil port of the second manual reversing valve and the rodless cavity of the single-rod hydraulic cylinder to form a pressure relief circuit for the rodless cavity of the hydraulic cylinder; the pressure relief device consists of a ball valve and a gas-isolated accumulator. The inlet port of the ball valve is connected to the oil circuit between the pilot-operated check valve and the flow-dividing valve in the flow-dividing pressure-holding device, and its outlet port is connected to the oil port of the gas-isolated accumulator and the rod cavity of the single-rod hydraulic cylinder to release the pressure in the rodless cavity of the single-rod hydraulic cylinder.

[0010] The inner arc surfaces of the arc-shaped tooth plates in the front jaw plate assembly and the rear jaw plate assembly enclose the clamped pipe diameter, and the total circumferential angle formed by the enclosure of the arc-shaped tooth plates on the two front jaw plate assemblies and the rear jaw plate assemblies is set between 240° and 300°.

[0011] The arc-shaped tooth plate is made of a non-metallic material.

[0012] Preferably, the hydraulic control system further includes a quick-connect mechanical interlock protection device, an up-unthreading direction protection device, and a quick-connect hydraulic interlock protection device;

[0013] The quick-connect mechanical interlock protection device includes a quick-connect combination assembly, a connecting cable, a flexible shaft, a bracket, a spring, and a flexible shaft gate valve. One end of the flexible shaft is connected to the wrench in the quick-connect combination assembly through the connecting cable, and the other end is connected to the flexible shaft gate valve. The bracket is fixed to the flexible shaft gate valve, and the spring is arranged in series in the flexible shaft and abuts between the bracket and the flexible shaft gate valve;

[0014] The above-mentioned make-and-break direction protection device includes a third manual reversing valve and two pilot-operated check valves. The third manual reversing valve is included in the manual reversing combination valve. The two pilot-operated check valves are respectively connected in series at the inlet and outlet ports of the hydraulic motor in the hydraulic motor control circuit, and the fluid flow directions of the pilot-operated check valves both point to the hydraulic motor. The two working oil ports of the third manual reversing valve are respectively communicated with the pilot ports on the two pilot-operated check valves. When the spool in the third manual reversing valve is in the middle position, the two pilot-operated check valves are both in the closed state, and the oil circuit of the hydraulic motor control circuit is not connected. Push the third manual reversing valve, and the hydraulic oil flows from one working oil port of the third manual reversing valve to the pilot port of one pilot-operated check valve. This oil circuit opens a two-way passage, and the pilot port of the other pilot-operated check valve is communicated with the return oil of the hydraulic control system through the other working oil port of the third manual reversing valve. The oil circuit where it is located is unidirectionally closed and unidirectionally connected. Only the oil circuit rotating in the make-up direction in the hydraulic motor control circuit is connected, and the oil circuit rotating in the break-out direction is closed. On the contrary, pull the third manual reversing valve, and only the oil circuit rotating in the break-out direction in the hydraulic motor control circuit is connected, and the oil circuit rotating in the make-up direction is closed;

[0015] The quick-connect hydraulic interlock protection device includes a quick-connect combination assembly and two pilot-operated check valves in the make-and-break direction protection device. The female combination joints on the quick-connect combination assembly are respectively communicated with the pilot ports on the two pilot-operated check valves and the return oil port of the hydraulic control system, and the corresponding male combination joints are converged and connected.

[0016] Preferably, a front jaw plate return torsion spring is provided in the hydraulic cylinder lever clamping type jaw head. The front jaw plate return torsion spring is strung on the pin, and one end extends out and is fixed on the front jaw plate, and the other end extends out and blocks on the large gear at the opening of the jaw head, forming an automatic reset mechanism for the front jaw plate assembly.

[0017] Preferably, a clamping arm automatic reset mechanism is provided in the hydraulic cylinder lever clamping type jaw head. The clamping arm automatic reset mechanism includes a setscrew, bolt (1), an adjusting block, a tension spring and bolt (2). Bolt (1) is fixed on the large gear at the opening of the jaw head, and bolt (2) is fixed on the clamping arm. There is an adjusting groove on the adjusting block. The setscrew is screwed at one end of the adjusting groove, and the tension spring is connected to the other end of the adjusting block. The adjusting groove on the adjusting block is sleeved on bolt (1), and the setscrew abuts against the outer circle of bolt (1). The other end of the tension spring is connected to bolt (2) on the clamping arm.

[0018] Preferably, a disc spring is provided in the single-rod hydraulic cylinder. The disc spring is arranged in the rod chamber to form an automatic reset mechanism for the single-rod.

[0019] Preferably, in order to reduce the structural size under the same clamping force, a hydraulic booster device is connected in parallel between the flow dividing and pressure maintaining device and the quick-connect combination assembly connected thereto. The hydraulic booster device and the flow dividing and pressure maintaining device are integrated into an integral valve group.

[0020] Preferably, the non-metallic material is asbestos-free copper wire wear-resistant resin.

[0021] Preferably, the non-metallic material is oil-resistant rubber.

[0022] Preferably, a positioning device is provided on the valve core of the third manual reversing valve.

[0023] The present invention uses a lever clamping mechanism driven by a hydraulic cylinder for clamping. When the rodless cavity of the single-rod hydraulic cylinder is filled with hydraulic oil, the single rod in the single-rod hydraulic cylinder extends to push the clamping arm to rotate around the rotating shaft, driving the front jaw plate assembly at the other end of the clamping arm to approach the rotation center of the large gear at the opening of the tong head until the two front jaw plate assemblies and one rear jaw plate assembly close together to tightly hold the pipe string. It has a large clamping force, is stable and reliable. The present invention also uses a pluggable oil supply and return system and a pressure relief device with an accumulator to solve the problems of rotating oil supply and return of the tong head clamping mechanism. The quick-connect combination assembly can make multiple quick connectors plugged in or unplugged simultaneously, with quick and convenient operation. The pressure relief device is to solve the problem that the opening of the hydraulic cylinder lever clamping type tong head cannot be normally centered and reset during the make-up operation: when the make-up reaches the set torque and the pipe string thread has been made up, at this time, the hydraulic cylinder lever clamping type tong head stops rotating and stops at any position of 360°, while the single-rod hydraulic cylinder is still in the pressure-holding state and always tightly holds the pipe string. If we want to center the opening of the hydraulic cylinder lever clamping type tong head, either continue to rotate beyond the set make-up torque value to damage the thread, or reverse rotate to loosen the made-up thread, such operations are not allowed. Therefore, when it is necessary to relieve the pressure in the rodless cavity of the single-rod hydraulic cylinder, open the ball valve to allow the pressure oil in the rodless cavity of the single-rod hydraulic cylinder to flow to the rod cavity and the gas-isolated accumulator for unloading. At this time, the lever clamping mechanism driven by the hydraulic cylinder is in the loosened state, thus facilitating the operation of rotating the hydraulic cylinder lever clamping type tong head to center the opening. After the rodless cavity of the single-rod hydraulic cylinder is unloaded, close the ball valve to cut off the oil circuit between the rodless cavity of the single-rod hydraulic cylinder and the rod cavity and the gas-isolated accumulator, and the single-rod hydraulic cylinder returns to the normal working state.

[0024] The present invention also adopts a quick-connect mechanical interlock protection device, a make-up and break-out direction protection device, and a quick-connect hydraulic interlock protection device to ensure the safety and reliability of operations. Among them, the quick-connect mechanical interlock protection device and the quick-connect hydraulic interlock protection device provide double protection for the quick-connect combination assembly: when the female combination joint is connected to the male combination joint, the flexible shaft in the quick-connect mechanical interlock protection device pulls the flexible shaft gate valve to change the direction, and the hydraulic motor control circuit is in the unloading state. At the same time, the hydraulic control ports of the two hydraulic control one-way valves in the make-up and break-out direction protection device are connected to the oil return port of the hydraulic control system, the two hydraulic control one-way valves are closed, and the oil path leading to the hydraulic motor is cut off. The hydraulic motor control circuit is in the unloading and locked state, ensuring that the hydraulic motor cannot rotate when the quick-connect combination assembly is connected, and avoiding potential safety hazards caused by misoperation; when the female combination joint is separated from the male combination joint, the spring in the quick-connect mechanical interlock protection device pushes the flexible shaft gate valve to return to its original position. At the same time, the hydraulic control ports of the two hydraulic control one-way valves in the make-up and break-out direction protection device are not affected by the quick-connect combination assembly, and the hydraulic motor control circuit is in the normal working state. The make-up and break-out direction protection device ensures that only one of the continuous push or pull operations of the first manual reversing valve controlling the hydraulic motor is effective. Only the oil path for the hydraulic motor to rotate in one direction is open, while the oil path for the other rotation direction is blocked, avoiding the wrong operation of breaking the connection by reverse rotation when pulling the first manual reversing valve before the pipe string thread is tightened and the rodless cavity of the single-rod hydraulic cylinder has not been depressurized during the make-up operation; if you want to switch to the other rotation direction, you need to switch the position of the spool in the third manual reversing valve.

[0025] Secondly, the present invention uses a taller and larger die to increase the friction area, selects a wear-resistant non-metallic material to increase the friction force, and does not damage the surface of the pipe string, meeting the need for non-scratch operation.

[0026] The specific operation methods during the make-up and break-out operations of this technical solution are as follows:

[0027] Step 1. Clamping the pipe string operation: First, open the safety door of the main clamp of the power tong, push the main clamp of the power tong to the center of the pipe string, close the safety door, and then operate the wrench to connect the female combination joint to the male combination joint. At this time, under the double protection of the quick-connect mechanical interlock protection device and the quick-connect hydraulic interlock protection device, the hydraulic motor control circuit is in the unloading and locked state;

[0028] Push the second manual reversing valve to supply hydraulic oil to the rodless cavities of the two single-rod hydraulic cylinders through the shunt pressure-holding device, driving the two groups of lever clamping mechanisms to clamp the pipe string at the same time; operate the second manual reversing valve to return to the middle position, and the shunt pressure-holding device holds the pressure oil in the rodless cavities of the single-rod hydraulic cylinders to maintain the clamping of the pipe string; then operate the wrench to separate the female combination joint from the male combination joint, and the quick-connect mechanical interlock protection device and the quick-connect hydraulic interlock protection device are unlocked at the same time. At this time, the rotation direction of the hydraulic motor is restricted by the make-up and break-out direction protection device, and the next make-up or break-out operation is selected according to the operation requirements.

[0029] Step Two: Operation of making and breaking joints:

[0030] a. Operation of making a joint: Push the third manual directional control valve to the position for making a joint control, then push the first manual directional control valve. The hydraulic motor rotates, and the clamp head of the hydraulic cylinder lever clamping type clamps the pipe string and rotates in the direction of making a joint until the make-up torque reaches the set value and stops rotating; Operate the first manual directional control valve to return to the neutral position, operate the ball valve to open, unload the pressure oil retained in the rodless cavity of the single-rod hydraulic cylinder and then close the ball valve, and then pull the first manual directional control valve to make the clamp head of the hydraulic cylinder lever clamping type rotate in the reverse direction until its opening is centered;

[0031] b. Operation of breaking a joint: Pull the third manual directional control valve to the position for breaking a joint control, then pull the first manual directional control valve. The hydraulic motor rotates in the reverse direction, and the clamp head of the hydraulic cylinder lever clamping type clamps the pipe string and rotates in the direction of breaking a joint until the upper and lower pipe strings are disengaged. Continue to pull the first manual directional control valve, and the clamp head of the hydraulic cylinder lever clamping type continues to rotate until the opening is centered;

[0032] Step Three: Operation of resetting the clamping mechanism: Operate the wrench to connect the female combined joint with the male combined joint, pull the second manual directional control valve to supply oil to the rod cavity of the single-rod hydraulic cylinder. The single rod of the single-rod hydraulic cylinder retracts, and the lever clamping mechanism driven by the hydraulic cylinder loosens; Operate the second manual directional control valve to return to the neutral position. The rodless cavity and the rod cavity of the single-rod hydraulic cylinder are both connected to the return oil of the hydraulic control system, and the gas-isolated accumulator discharges the stored hydraulic oil to prepare for the next oil storage;

[0033] Finally, open the safety door, and the main clamp of the power tong leaves the center of the pipe string, and one operation of making or breaking a joint is completed.

[0034] The present invention adopts a lever clamping mechanism driven by a hydraulic cylinder to provide a greater clamping force, with a compact structure and reliable clamping; Adopts a pluggable oil supply and return system and a pressure relief device with an accumulator to meet the requirements of the rotation oil supply and return of the clamp head clamping mechanism; Adopts multi-faceted safety guarantee measures to ensure the safety and reliability of the operation; At the same time, the tooth plate is made higher and larger, thereby increasing the friction area; Further selects wear-resistant non-metallic materials to increase the friction force to achieve sufficient torque and realize the operation without tooth marks on special pipes. Its operation is stable, safe and reliable, and has great economic and social benefits. Description of the Drawings

[0035] Figure 1 is the front view of the present invention;

[0036] Figure 2 is the top view of the present invention;

[0037] Figure 3 is the top view (half-section) of the clamp head of the hydraulic cylinder lever clamping type;

[0038] Figure 4 The Figure 3 B - B view;

[0039] Figure 5 is the hydraulic schematic diagram of the present invention;

[0040] Figure 6 is the top view of the front jaw plate assembly;

[0041] Figure 7 is Figure 6 the C - C view (rotated) of

[0042] Figure 8 is the top view of the rear jaw plate assembly;

[0043] Figure 9 is Figure 8 the D - D view (rotated) of

[0044] Figure 10 is the hydraulic schematic diagram of the present invention including a quick - connect mechanical interlock protection device, a make - break direction protection device, and a quick - connect hydraulic interlock protection device;

[0045] Figure 11 is the schematic diagram (partial view) of the quick - connect mechanical interlock protection device when the quick - connect assembly is separated;

[0046] Figure 12 is the top view (sectioned) of the hydraulic cylinder lever - clamping type tong head including a front jaw plate return torsion spring, a clamping arm automatic return mechanism, and a disc spring in a single - rod hydraulic cylinder;

[0047] Figure 13 is the top view (sectioned) of the clamping arm automatic return mechanism;

[0048] Figure 14 is the hydraulic schematic diagram of the present invention including a hydraulic booster device and a disc spring.

[0049] In the figure: 1. Hydraulic cylinder lever clamping type tong head; 101. Large gear for tong head opening; 102. Single-rod hydraulic cylinder; 102Ⅰ. Single-rod head; 102Ⅱ. Disc spring; 103. Clamping arm; 104. Rotating shaft; 105. Front jaw plate assembly; 105Ⅰ. Front jaw plate; 105Ⅱ. Arc-shaped tooth plate; 106. Plug pin; 107. Rear jaw plate assembly; 107Ⅰ. Rear jaw plate; 108. Limit block; 109. Reset torsion spring for front jaw plate; 110. Automatic reset mechanism for clamping arm; 110Ⅰ. Set screw; 110Ⅱ. Bolt ㈠; 110Ⅲ. Adjusting block; 110Ⅳ. Tension spring; 110Ⅴ. Bolt ㈡; 2. Housing; 3. Safety door; 4. Power transmission system; 401. Hydraulic motor; 402. Transmission gear; 5. Hydraulic control system; 501. Manual reversing combination valve; 501Ⅰ. First manual reversing valve; 501Ⅱ. Second manual reversing valve; 501Ⅲ. Third manual reversing valve; 502. Quick-connect combination assembly; 502Ⅰ. Male combination joint; 502Ⅱ. Female combination joint; 502Ⅲ. Wrench; 503. Pressure relief device; 503Ⅰ. Ball valve; 503Ⅱ. Gas isolation type accumulator; 504. Flow splitting and pressure maintaining device; 504Ⅰ. Flow splitting valve; 504Ⅱ. Hydraulic control one-way valve; 505. Hydraulic boosting device; 506. Quick-connect mechanical interlock protection device; 506Ⅰ. Connecting cable; 506Ⅱ. Flexible shaft; 506Ⅲ. Bracket; 506Ⅳ. Spring; 506Ⅴ. Flexible shaft gate control valve; 507. Make-up and break-out direction protection device; 507Ⅰ. Hydraulic control one-way valve; 508. Quick-connect hydraulic interlock protection device; a. Inner arc; b. Back; c. Adjusting groove. Detailed implementation manners

[0050] The present invention will be further explained below with reference to the accompanying drawings:

[0051] As Figure 1 、 2As shown in Figures 3, 4, and 5, the present invention includes a hydraulic cylinder lever clamping type jaw 1, a housing 2, a safety door 3, a power transmission system 4, and a hydraulic control system 5. The power transmission system 4 is arranged at the rear of the housing 2, and the safety door 3 is arranged at the front opening of the housing 2. The power transmission system 4 includes a hydraulic motor 401 and a transmission gear 402. The hydraulic motor 401 transmits power to the hydraulic cylinder lever clamping type jaw 1 through the transmission gear 402. The hydraulic cylinder lever clamping type jaw 1 is arranged at the front of the housing 2, and it includes a large jaw opening gear 101, a single rod hydraulic cylinder 102, a clamping arm 103, a rotating shaft 104, a front jaw plate assembly 105, a pin 106, a rear jaw plate assembly 107, and a limit block 108. The single rod hydraulic cylinder 102, the clamping arm 103, the rotating shaft 104, and the pin 106 form a set of lever clamping mechanisms driven by a hydraulic cylinder, and there are two sets of lever clamping mechanisms driven by a hydraulic cylinder. The two sets of lever clamping mechanisms driven by a hydraulic cylinder are arranged inside the large jaw opening gear 101 and are symmetrically arranged along the axis A-A symmetrical to the opening of the large jaw opening gear 101. The single rod hydraulic cylinder 102 is fastened to the large jaw opening gear 101. The clamping arm 103 forms a fixed hinge rotating pair with the large jaw opening gear 101 through the rotating shaft 104. The single rod hydraulic cylinder 102 includes a single rod head 102Ⅰ, and its single rod head 102Ⅰ abuts against one end of the clamping arm 103. The other end of the clamping arm 103 is provided with a pin 106. The front jaw plate assembly 105 is strung on the pin 106 to form a movable hinge of a rotating pair, and it includes a front jaw plate 105Ⅰ and an arc-shaped tooth plate 105Ⅱ;

[0052] The rear jaw plate assembly 107 includes a rear jaw plate 107Ⅰ and an arc-shaped tooth plate 105Ⅱ. Its central plane D-D coincides with the cross-section of the axis A-A symmetrical to the opening of the large jaw opening gear 101. Its back b fits and is fastened to the inner arc a of the large jaw opening gear 101. The two sides of the rear jaw plate assembly 107 are limited by limit blocks 108, and the limit blocks 108 are fixed to the large jaw opening gear 101 as a whole;

[0053] The hydraulic control system 5 includes a manual reversing combination valve 501, a quick-connect combination assembly 502, a pressure relief device 503, and a flow splitting and pressure maintaining device 504. The manual reversing combination valve 501 includes a first manual reversing valve 501Ⅰ and a second manual reversing valve 501Ⅱ. The quick-connect combination assembly 502 includes a male combination joint 502Ⅰ, a female combination joint 502Ⅱ, and a wrench 502Ⅲ. By operating the wrench 502Ⅲ, the male combination joint 502Ⅰ and the female combination joint 502Ⅱ are separated or connected. The manual reversing combination valve 501 and the female combination joint 502Ⅱ are arranged on the housing 2. The flow splitting and pressure maintaining device 504, the pressure relief device 503, and the male combination joint 502Ⅰ are arranged on the hydraulic cylinder lever clamping type jaw 1;

[0054] The first manual reversing valve 501Ⅰ is connected to the oil ports of the hydraulic motor 401 to form a hydraulic motor control circuit, which controls the forward and reverse rotation of the hydraulic motor 401, driving the rotation of the hydraulic cylinder lever clamping jaw 1. When pushing the first manual reversing valve 501Ⅰ, the hydraulic cylinder lever clamping jaw 1 rotates in the make-up direction; when pulling the first manual reversing valve 501Ⅰ, the hydraulic cylinder lever clamping jaw 1 rotates in the unmake-up direction;

[0055] The second manual reversing valve 501Ⅱ is connected to the single-rod hydraulic cylinder 102 through the quick-connect combination assembly 502 and the flow-dividing pressure-holding device 504 to form a single-rod hydraulic cylinder control circuit; the flow-dividing pressure-holding device 504 is arranged between one oil port of the second manual reversing valve 501Ⅱ and the rodless cavity of the single-rod hydraulic cylinder 102, and it consists of a flow-dividing valve 504Ⅰ and a hydraulic control one-way valve 504Ⅱ. Among them, the oil inlet of the hydraulic control one-way valve 504Ⅱ is connected to the male combination joint 502Ⅰ connecting one oil port of the second manual reversing valve 501Ⅱ, the liquid flow direction of its hydraulic control one-way valve 504Ⅱ points to the single-rod hydraulic cylinder 102, its oil outlet is connected to the oil inlet of the flow-dividing valve 504Ⅰ, its hydraulic control port is connected to the male combination joint 502Ⅰ connecting the other oil port of the second manual reversing valve 501Ⅱ, and the two oil outlets of its flow-dividing valve 504Ⅰ are respectively connected to the rodless cavities of the two single-rod hydraulic cylinders 102; the other oil port of the second manual reversing valve 501Ⅱ is connected to the rod chamber of the single-rod hydraulic cylinder 102 through the quick-connect combination assembly 502; when pushing the second manual reversing valve 501Ⅱ, the hydraulic oil flows through the flow-dividing pressure-holding device 504 to the rodless cavity of the single-rod hydraulic cylinder 102, and the single-rod hydraulic cylinder 102 extends; when pulling the second manual reversing valve 501Ⅱ, the hydraulic oil flows to the rod chamber of the single-rod hydraulic cylinder 102, and the single-rod hydraulic cylinder 102 retracts;

[0056] The pressure relief device 503 is arranged in the oil circuit between one oil port of the second manual reversing valve 501Ⅱ and the rodless cavity of the single-rod hydraulic cylinder 102 to form a pressure relief circuit for the rodless cavity of the hydraulic cylinder; the pressure relief device 503 consists of a ball valve 503Ⅰ and a gas-isolated accumulator 503Ⅱ. Among them, the oil inlet of the ball valve 503Ⅰ is connected to the oil path between the hydraulic control one-way valve 504Ⅱ and the flow-dividing valve 504Ⅰ in the flow-dividing pressure-holding device 504, and its oil outlet is connected to the oil port of the gas-isolated accumulator 503Ⅱ and the rod chamber of the single-rod hydraulic cylinder 102 to release the pressure in the rodless cavity of the single-rod hydraulic cylinder 102.

[0057] As Figure 3 、 4 As shown in Figures 6, 7, 8, 9, and 12, the inner arc surface of the arc-shaped tooth plate 105Ⅱ in the front jaw plate assembly 105 and the rear jaw plate assembly 107 encloses the diameter of the clamped object, and the total circumferential angle formed by the enclosing of the arc-shaped tooth plates 105Ⅱ on the two front jaw plate assemblies 105 and the rear jaw plate assemblies 107 is set between 240° and 300°.

[0058] AsFigure 6 , 7 As shown in FIGS. 8 and 9, the arc-shaped tooth plate 105Ⅱ is made of non-metallic material.

[0059] As Figure 10 , 11 shown, preferably, the hydraulic control system 5 further includes a quick-connect mechanical interlock protection device 506, a make-up and break-out direction protection device 507, and a quick-connect hydraulic interlock protection device 508;

[0060] The quick-connect mechanical interlock protection device 506 includes a quick-connect assembly 502, a connecting cable 506Ⅰ, a flexible shaft 506Ⅱ, a bracket 506Ⅲ, a spring 506Ⅳ, and a flexible shaft gate valve 506Ⅴ. One end of the flexible shaft 506Ⅱ is connected to the wrench 502Ⅲ in the quick-connect assembly 502 through the connecting cable 506Ⅰ, and the other end is connected to the flexible shaft gate valve 506Ⅴ. The bracket 506Ⅲ is fixed to the flexible shaft gate valve 506Ⅴ. The spring 506Ⅳ is sleeved in the flexible shaft 506Ⅱ and abuts between the bracket 506Ⅲ and the flexible shaft gate valve 506Ⅴ;

[0061] The make-up and break-out direction protection device 507 includes a third manual reversing valve 501Ⅲ and two hydraulic control check valves 507Ⅰ. The third manual reversing valve 501Ⅲ is included in the manual reversing combination valve 501. The two hydraulic control check valves 507Ⅰ are respectively connected in series at the inlet and outlet ports of the hydraulic motor 401 in the hydraulic motor control circuit. The flow direction of the hydraulic control check valve 507Ⅰ is towards the hydraulic motor 401. The two working oil ports of the third manual reversing valve 501Ⅲ are respectively connected to the hydraulic control ports on the two hydraulic control check valves 507Ⅰ. When the spool in the third manual reversing valve 501Ⅲ is in the middle position, the two hydraulic control check valves 507Ⅰ are both in the closed state, and the oil circuit of the hydraulic motor control circuit is blocked. Push the third manual reversing valve 501Ⅲ, and the hydraulic oil flows from one working oil port of the third manual reversing valve 501Ⅲ to the hydraulic control port of one of the hydraulic control check valves 507Ⅰ. This oil circuit is opened for two-way communication. The hydraulic control port of the other hydraulic control check valve 507Ⅰ is connected to the return oil of the hydraulic control system 5 through the other working oil port of the third manual reversing valve 501Ⅲ. The oil circuit where it is located is unidirectionally closed and unidirectionally open. Only the oil circuit rotating in the make-up direction in the hydraulic motor control circuit is open, and the oil circuit rotating in the break-out direction is closed. Conversely, pull the third manual reversing valve 501Ⅲ, and only the oil circuit rotating in the break-out direction in the hydraulic motor control circuit is open, and the oil circuit rotating in the make-up direction is closed;

[0062] The quick-connect hydraulic interlock protection device 508 includes the quick-connect assembly 502 and the two hydraulic control check valves 507Ⅰ in the make-up and break-out direction protection device 507. The female combination joint 502Ⅱ on the quick-connect assembly 502 is respectively connected to the hydraulic control ports on the two hydraulic control check valves 507Ⅰ and the return oil port of the hydraulic control system 5, and the corresponding male combination joints 502Ⅰ are converged and connected.

[0063] AsFigure 12 As shown, preferably, a front jaw plate return torsion spring 109 is provided in the hydraulic cylinder lever clamping type jaw head 1. The front jaw plate return torsion spring 109 is strung on the pin 106, with one end extending out and fixed on the front jaw plate 105Ⅰ, and the other end extending out and blocking on the large gear 101 at the opening of the jaw head, forming an automatic return mechanism for the front jaw plate assembly.

[0064] As Figure 12 、 14 As shown, preferably, a clamping arm automatic return mechanism 110 is provided in the hydraulic cylinder lever clamping type jaw head 1. The clamping arm automatic return mechanism 110 includes a setscrew 110Ⅰ, a bolt (Ⅰ) 110Ⅱ, an adjusting block 110Ⅲ, a tension spring 110Ⅳ and a bolt (Ⅱ) 110Ⅴ. The bolt (Ⅰ) 110Ⅱ is fixed on the large gear 101 at the opening of the jaw head, and the bolt (Ⅱ) 110Ⅴ is fixed on the clamping arm 103; there is an adjusting groove c on the adjusting block 110Ⅲ, the setscrew 110Ⅰ is screwed at one end of the adjusting groove c, and the tension spring 110Ⅳ is connected to the other end of the adjusting block 110Ⅲ; the adjusting groove c on the adjusting block 110Ⅲ is sleeved on the bolt (Ⅰ) 110Ⅱ, and the setscrew 110Ⅰ abuts against the outer circle of the bolt (Ⅰ) 110Ⅱ; the other end of the tension spring 110Ⅳ is connected to the bolt (Ⅱ) 110Ⅴ on the clamping arm 103.

[0065] As Figure 10 、 12 As shown, preferably, a disc spring 102Ⅱ is provided in the single-rod hydraulic cylinder 102. The disc spring 102Ⅱ is arranged in the rod chamber, forming an automatic return mechanism for the single-rod.

[0066] As Figure 14 As shown, preferably, in order to reduce the structural size under the same clamping force, a hydraulic boosting device 505 is provided in parallel between the flow dividing and pressure maintaining device 504 and the quick-connect combination assembly 502 connected thereto. The hydraulic boosting device 505 and the flow dividing and pressure maintaining device 504 are integrated into an integral valve group.

[0067] As Figure 6 、 7 As shown in Figures 8 and 9, preferably, the non-metallic material is asbestos-free copper wire wear-resistant resin.

[0068] As Figure 6 、 7 As shown in Figures 8 and 9, preferably, the non-metallic material is oil-resistant rubber.

[0069] As Figure 10 As shown, preferably, a positioning device is provided on the valve core of the third manual reversing valve 501Ⅲ.

[0070] The present invention uses a lever clamping mechanism driven by a hydraulic cylinder for clamping. When the rodless cavity of the single-rod hydraulic cylinder 102 is filled with hydraulic oil, the single rod in the single-rod hydraulic cylinder 102 extends to push the clamping arm 103 to rotate around the rotating shaft 104, driving the front jaw plate assembly 105 at the other end of the clamping arm 103 to approach the rotation center of the large gear 101 at the opening of the tong head until the two front jaw plate assemblies 105 and a rear jaw plate assembly 107 close together to tightly hold the pipe string. It has a large clamping force, is stable and reliable. The present invention also adopts a pluggable oil supply and return system and a pressure relief device 503 with an accumulator to solve the problems of rotating oil supply and return for the clamping mechanism of the tong head. The quick-connect combination assembly 502 can make multiple quick connectors plugged in or unplugged simultaneously, with quick and convenient operation. The pressure relief device 503 is to solve the problem that the opening of the hydraulic cylinder lever clamping type tong head 1 cannot be normally centered and reset during the make-up operation: when the make-up reaches the set torque and the pipe string thread has been made up, at this time, the hydraulic cylinder lever clamping type tong head 1 stops rotating and stops at any position of 360°, while the single-rod hydraulic cylinder 102 is still in the pressure-holding state and always holds the pipe string tightly. If we want to center the opening of the hydraulic cylinder lever clamping type tong head 1, either continue to rotate beyond the set make-up torque value to damage the thread, or rotate in the reverse direction to loosen the made-up thread. Such operations are not allowed. Therefore, when it is necessary to relieve the pressure in the rodless cavity of the single-rod hydraulic cylinder 102, open the ball valve 503Ⅰ, so that the pressure oil in the rodless cavity of the single-rod hydraulic cylinder 102 flows to the rod cavity and the gas-separated accumulator 503Ⅱ for unloading. At this time, the lever clamping mechanism driven by the hydraulic cylinder is in the loosened state, thus facilitating the operation of rotating the hydraulic cylinder lever clamping type tong head 1 to center the opening. After the rodless cavity of the single-rod hydraulic cylinder 102 is unloaded, close the ball valve 503Ⅰ to cut off the oil circuit between the rodless cavity of the single-rod hydraulic cylinder 102 and the rod cavity and the gas-separated accumulator 503Ⅱ, and the single-rod hydraulic cylinder 102 returns to the normal working state.

[0071] The present invention also adopts a quick-connect mechanical interlock protection device 506, a make-up and break-out direction protection device 507, and a quick-connect hydraulic interlock protection device 508 to ensure the safety and reliability of operations. Among them, the quick-connect mechanical interlock protection device 506 and the quick-connect hydraulic interlock protection device 508 provide double protection for the quick-connect combination assembly 502: when the female combination joint 502Ⅱ is connected to the male combination joint 502Ⅰ, the flexible shaft 506Ⅱ in the quick-connect mechanical interlock protection device 506 pulls the flexible shaft gate valve 506Ⅴ to change the direction, and the hydraulic motor control circuit is in the unloading state. At the same time, the hydraulic control ports of the two hydraulic control check valves 507Ⅰ in the make-up and break-out direction protection device 507 are connected to the oil return port of the hydraulic control system 5, and the two hydraulic control check valves 507Ⅰ are closed, cutting off the oil circuit leading to the hydraulic motor 401. The hydraulic motor control circuit is in the unloading and locked state, ensuring that when the quick-connect combination assembly 502 is connected, the hydraulic motor 401 cannot rotate, avoiding potential safety hazards caused by misoperation; when the female combination joint 502Ⅱ is separated from the male combination joint 502Ⅰ, the spring 506Ⅳ in the quick-connect mechanical interlock protection device 506 pushes the flexible shaft gate valve 506Ⅴ to return to its original position. At the same time, the hydraulic control ports of the two hydraulic control check valves 507Ⅰ in the make-up and break-out direction protection device 507 are not affected by the quick-connect combination assembly 502, and the hydraulic motor control circuit is in the normal working state. The make-up and break-out direction protection device 507 ensures that only one of the continuous push or pull operations of the first manual reversing valve 501Ⅰ controlling the hydraulic motor 401 is effective. Only the oil circuit for the hydraulic motor 401 to rotate in one direction is open, while the oil circuit for the other rotation direction is blocked, avoiding the wrong operation of reverse rotation and break-out when the pipe string thread has been well made up during the make-up operation, and the rodless cavity of the single-rod hydraulic cylinder 102 has not been depressurized yet and the first manual reversing valve 501Ⅰ is pulled; if it is necessary to switch to the other rotation direction, the position of the spool in the third manual reversing valve 501Ⅲ needs to be switched.

[0072] Secondly, the present invention uses a taller and larger die plate to increase the friction area, selects wear-resistant non-metallic materials to increase the friction force, and does not damage the surface of the pipe string, meeting the need for non-scratch operation.

[0073] The specific operation methods during the make-up and break-out operations of this technical solution are as follows:

[0074] Step 1. Clamp the pipe string operation: First, open the safety door 3 of the power tong main tong, push the power tong main tong to the center of the pipe string, close the safety door 3, and then operate the wrench 502Ⅲ to connect the female combination joint 502Ⅱ to the male combination joint 502Ⅰ. At this time, under the double protection of the quick-connect mechanical interlock protection device 506 and the quick-connect hydraulic interlock protection device 508, the hydraulic motor control circuit is in the unloading and locked state;

[0075] Push the second manual reversing valve 501Ⅱ to supply hydraulic oil to the rodless cavities of the two single-rod hydraulic cylinders 102 through the flow dividing and pressure maintaining device 504, driving the two groups of lever clamping mechanisms to clamp the pipe string simultaneously; operate the second manual reversing valve 501Ⅱ to return to the middle position, and the flow dividing and pressure maintaining device 504 maintains the pressure oil in the rodless cavity of the single-rod hydraulic cylinder 102 to keep the pipe string clamped; then operate the wrench 502Ⅲ to separate the female combined joint 502Ⅱ from the male combined joint 502Ⅰ, and the quick-connect mechanical interlock protection device 506 and the quick-connect hydraulic interlock protection device 508 are unlocked simultaneously. At this time, the rotation direction of the hydraulic motor 401 is restricted by the make-up and break-out direction protection device 507, and the next make-up or break-out operation is selected according to the operation requirements;

[0076] Step 2. Make-up and break-out operation:

[0077] a. Make-up operation: Push the third manual reversing valve 501Ⅲ to the make-up control direction, and then push the first manual reversing valve 501Ⅰ. The hydraulic motor 401 rotates, and the hydraulic cylinder lever clamping type tong head 1 clamps the pipe string and rotates in the make-up direction until the make-up torque reaches the set value and stops rotating; operate the first manual reversing valve 501Ⅰ to return to the middle position, operate the ball valve 503Ⅰ to open, unload the pressure oil stored in the rodless cavity of the single-rod hydraulic cylinder 102 and then close the ball valve 503Ⅰ, and then pull the first manual reversing valve 501Ⅰ to make the hydraulic cylinder lever clamping type tong head 1 rotate reversely until its opening is centered;

[0078] b. Break-out operation: Pull the third manual reversing valve 501Ⅲ to the break-out control direction, and then pull the first manual reversing valve 501Ⅰ. The hydraulic motor 401 rotates reversely, and the hydraulic cylinder lever clamping type tong head 1 clamps the pipe string and rotates in the break-out direction until the upper and lower pipe strings are separated. Continue to pull the first manual reversing valve 501Ⅰ, and the hydraulic cylinder lever clamping type tong head 1 continues to rotate until the opening is centered;

[0079] Step 3. Clamping mechanism reset operation: Operate the wrench 502Ⅲ to connect the female combined joint 502Ⅱ with the male combined joint 502Ⅰ, pull the second manual reversing valve 501Ⅱ to supply oil to the rod cavity of the single-rod hydraulic cylinder 102, and the single rod of the single-rod hydraulic cylinder 102 retracts, and the lever clamping mechanism driven by the hydraulic cylinder loosens; operate the second manual reversing valve 501Ⅱ to return to the middle position, and the rodless cavity and the rod cavity of the single-rod hydraulic cylinder 102 are both connected to the return oil of the hydraulic control system 5, and the gas isolation type accumulator 503Ⅱ discharges the stored hydraulic oil to prepare for the next oil storage;

[0080] Finally, open the safety door 3, and the main tong of the power tong leaves the center of the pipe string, and one make-up or break-out operation is completed.

Claims

1. An open-type toothless power tong main tong, comprising a hydraulic cylinder lever clamping type tong head, a housing, a safety door, a power transmission system and a hydraulic control system. The power transmission system is arranged at the rear of the housing, and the safety door is arranged at the front opening of the housing. The power transmission system comprises a hydraulic motor and a transmission gear. The hydraulic motor transmits power to the hydraulic cylinder lever clamping type tong head through the transmission gear. It is characterized in that: The hydraulic cylinder lever clamping type tong head is arranged at the front of the housing. It comprises a large gear for tong head opening, a single-rod hydraulic cylinder, a clamping arm, a rotating shaft, a front jaw plate assembly, a pin, a rear jaw plate assembly and a limiting block. The single-rod hydraulic cylinder, the clamping arm, the rotating shaft and the pin form a group of lever clamping mechanisms driven by a hydraulic cylinder, and there are two groups of such lever clamping mechanisms driven by a hydraulic cylinder. The two groups of lever clamping mechanisms driven by a hydraulic cylinder are arranged in the inner cavity of the large gear for tong head opening and are symmetrically arranged along the axis A-A symmetrical to the opening of the large gear for tong head. The single-rod hydraulic cylinder is fastened to the large gear for tong head opening. The clamping arm forms a fixed hinge rotary pair with the large gear for tong head opening through the rotating shaft. The single-rod hydraulic cylinder comprises a single-rod head, and the single-rod head abuts against one end of the clamping arm. A pin is arranged at the other end of the clamping arm. The front jaw plate assembly is strung on the pin to form a movable hinge of a rotary pair, and it comprises a front jaw plate and an arc-shaped tooth plate. The rear jaw plate assembly comprises a rear jaw plate and an arc-shaped tooth plate. Its central plane D-D coincides with the cross-section of the axis A-A symmetrical to the opening of the large gear for tong head. Its back is attached and fastened to the inner arc of the large gear for tong head opening. The two sides of the rear jaw plate assembly are limited by limiting blocks, and the limiting blocks are fixed integrally with the large gear for tong head opening. The inner arc surfaces of the arc-shaped tooth plates in the front jaw plate assembly and the rear jaw plate assembly enclose the diameter of the clamped pipe, and the total circumferential angle formed by the enclosing of the arc-shaped tooth plates on the two front jaw plate assemblies and the rear jaw plate assemblies is set between 240° and 300°. The hydraulic control system comprises a manual reversing combination valve, a quick-connect combination assembly, a pressure relief device and a flow splitting and pressure maintaining device. The manual reversing combination valve comprises a first manual reversing valve and a second manual reversing valve. The quick-connect combination assembly comprises a male combination joint, a female combination joint and a wrench. The manual reversing combination valve and the female combination joint are arranged on the housing. The flow splitting and pressure maintaining device, the pressure relief device and the male combination joint are arranged on the hydraulic cylinder lever clamping type tong head. The first manual reversing valve is connected to the oil port of the hydraulic motor to form a hydraulic motor control circuit. The second manual directional control valve is connected to the single-rod hydraulic cylinder through a quick-connect combination assembly and a flow-dividing and pressure-holding device to form a control circuit for the single-rod hydraulic cylinder. The flow-dividing and pressure-holding device is arranged between one oil port of the second manual directional control valve and the rodless cavity of the single-rod hydraulic cylinder. It consists of a flow-dividing valve and a pilot-operated check valve. The inlet port of the pilot-operated check valve is connected to the male combination joint connecting one oil port of the second manual directional control valve. The flow direction of the pilot-operated check valve points to the single-rod hydraulic cylinder. Its outlet port is connected to the inlet port of the flow-dividing valve. Its pilot port is connected to the male combination joint connecting the other oil port of the second manual directional control valve. The two outlet ports of the flow-dividing valve are respectively connected to the rodless cavities of the two single-rod hydraulic cylinders. The other oil port of the second manual directional control valve is connected to the rod cavity of the single-rod hydraulic cylinder through a quick-connect combination assembly. The pressure relief device is arranged in the oil circuit between one oil port of the second manual directional control valve and the rodless cavity of the single-rod hydraulic cylinder to form a pressure relief circuit for the rodless cavity of the hydraulic cylinder. The pressure relief device consists of a ball valve and a gas-isolated accumulator. The inlet port of the ball valve is connected to the oil circuit between the pilot-operated check valve and the flow-dividing valve in the flow-dividing and pressure-holding device. Its outlet port is connected to the oil port of the gas-isolated accumulator and the rod cavity of the single-rod hydraulic cylinder. The hydraulic control system further includes a quick-connect mechanical interlock protection device, a make-up and break-out direction protection device, and a quick-connect hydraulic interlock protection device. The quick-connect mechanical interlock protection device includes a quick-connect combination assembly, a connecting cable, a flexible shaft, a bracket, a spring, and a flexible shaft gate valve. One end of the flexible shaft is connected to the wrench in the quick-connect combination assembly through the connecting cable, and the other end is connected to the flexible shaft gate valve. The bracket is fixed to the flexible shaft gate valve. The spring is arranged in series in the flexible shaft and abuts between the bracket and the flexible shaft gate valve. The make-up and break-out direction protection device includes a third manual directional control valve and two pilot-operated check valves. The third manual directional control valve is included in the manual directional control valve combination. The two pilot-operated check valves are respectively connected in series at the inlet and return oil ports of the hydraulic motor in the hydraulic motor control circuit. The flow direction of the pilot-operated check valves points to the hydraulic motor. The two working oil ports of the third manual directional control valve are respectively connected to the pilot ports on the two pilot-operated check valves. The quick-connect hydraulic interlock protection device includes a quick-connect combination assembly and two pilot-operated check valves in the make-up and break-out direction protection device. The female combination joints on the quick-connect combination assembly are respectively connected to the pilot ports on the two pilot-operated check valves and the return oil port of the hydraulic control system, and their corresponding male combination joints are joined together and connected.

2. The main pliers of an open - type tooth - mark - free power pliers according to claim 1, characterized in that: The arc-shaped jaw plate is made of non-metallic material.

3. The main pliers of an open-type toothless power pliers according to claim 1, characterized in that: A front jaw plate return torsion spring is arranged in the hydraulic cylinder lever clamping type jaw head. The front jaw plate return torsion spring is arranged in series on the pin. One end extends out and is fixed on the front jaw plate, and the other end extends out and abuts on the large gear at the opening of the jaw head to form an automatic reset mechanism for the front jaw plate assembly.

4. The main pliers of an open-type toothless power pliers according to claim 1, characterized in that: The clamping arm automatic reset mechanism is provided in the hydraulic cylinder lever clamping type tong head. The clamping arm automatic reset mechanism includes a setscrew, bolt (I), an adjusting block, a tension spring and bolt (II). The bolt (I) is fixed on the large gear at the opening of the tong head, and the bolt (II) is fixed on the clamping arm. An adjusting groove is provided on the adjusting block. The setscrew is screwed at one end of the adjusting groove, and the tension spring is connected to the other end of the adjusting block. The adjusting groove on the adjusting block is sleeved on the bolt (I), and the setscrew abuts against the outer circle of the bolt (I). The other end of the tension spring is connected to the bolt (II) on the clamping arm.

5. The main pliers of an open-type toothless power pliers according to claim 1, characterized in that: A disc spring is provided in the single-rod hydraulic cylinder. The disc spring is arranged in the rod chamber to form an automatic reset mechanism for the single-rod.

6. The main pliers of an open-type toothless power pliers according to claim 1, characterized in that: A hydraulic boosting device is provided in parallel between the flow dividing and pressure maintaining device and the quick-connect combined assembly connected thereto. The hydraulic boosting device and the flow dividing and pressure maintaining device are integrated into an integral valve group.

7. The main pliers of an open-type toothless power pliers according to claim 2, characterized in that: The non-metallic material is non-asbestos copper wire wear-resistant resin.

8. The main power tongs of an open type without tooth marks according to claim 2, further characterized in that: The non-metallic material is oil-resistant rubber.

9. The main pliers of an open-type toothless power pliers according to claim 1, characterized in that: A positioning device is provided on the valve core of the third manual reversing valve.

10. The control method of the toothless power tong main tong according to claim 1, characterized in that: Step 1, clamping string operation: First, open the safety door of the power tong main tong, push the power tong main tong to the center of the string, close the safety door, and then operate the wrench to connect the female combination joint and the male combination joint. At this time, protected by the double protection of the quick-connect mechanical interlock protection device and the quick-connect hydraulic interlock protection device, the hydraulic motor control circuit is in the unloading and locked state; Push the second manual reversing valve to supply hydraulic oil to the rodless chambers of the two single-rod hydraulic cylinders through the flow dividing and pressure maintaining device, and drive the two groups of lever clamping mechanisms to clamp the string at the same time; operate the second manual reversing valve to return to the middle position, and the flow dividing and pressure maintaining device keeps the pressure oil in the rodless chamber of the single-rod hydraulic cylinder to maintain the clamping of the string; then operate the wrench to separate the female combination joint and the male combination joint, and the quick-connect mechanical interlock protection device and the quick-connect hydraulic interlock protection device are unlocked at the same time. At this time, the rotation direction of the hydraulic motor is restricted by the make-up and break-out direction protection device, and the next make-up or break-out operation is selected according to the operation requirements; Step 2, make-up and break-out operation: a. Make-up operation: Push the third manual reversing valve to the make-up control direction, and then push the first manual reversing valve. The hydraulic motor rotates, and the hydraulic cylinder lever clamping type tong head clamps the string and rotates in the make-up direction until the make-up torque reaches the set value and stops rotating; operate the first manual reversing valve to return to the middle position, operate the ball valve to open, unload the pressure oil kept in the rodless chamber of the single-rod hydraulic cylinder and then close the ball valve, and then pull the first manual reversing valve to make the hydraulic cylinder lever clamping type tong head rotate in the reverse direction until its opening is centered; b. Break-out operation: Pull the third manual reversing valve to the break-out control direction, and then pull the first manual reversing valve. The hydraulic motor rotates in the reverse direction, and the hydraulic cylinder lever clamping type tong head clamps the string and rotates in the break-out direction until the upper and lower strings are separated. Continue to pull the first manual reversing valve, and the hydraulic cylinder lever clamping type tong head continues to rotate until the opening is centered; Step 3. Reset operation of the clamping mechanism: Operate the wrench to connect the female combined joint with the male combined joint, pull the second manual directional control valve to supply oil to the rod chamber of the single-rod hydraulic cylinder, the single rod of the single-rod hydraulic cylinder retracts, and the lever clamping mechanism driven by the hydraulic cylinder loosens; Operate the second manual directional control valve to return to the middle position, the rodless chamber and the rod chamber of the single-rod hydraulic cylinder are both connected to the return oil of the hydraulic control system, and the gas isolation type accumulator discharges the stored hydraulic oil to prepare for the next oil storage; Finally, open the safety door, and the main tong of the power tong leaves the center of the pipe string, and one make-up or breakout operation is completed.

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