Hydraulic system of internal welding machine

Abstract

The utility model provides a hydraulic system of an internal welding machine. A hydraulic pump is respectively connected with a brake cylinder loop, a walking cylinder loop, a front expansion cylinder loop, a rear expansion cylinder loop and a counterpart cylinder loop; the brake cylinder loop is connected with the two ends of the brake cylinder, the walking cylinder loop is connected with the two ends of the walking cylinder, the front expansion cylinder loop is connected with the two ends of the front expansion cylinder, the rear expansion cylinder loop is connected with the two ends of the rear expansion cylinder, and the counterpart cylinder loop is connected with the multiple counterpart cylinders. A first electromagnetic directional valve and a second electromagnetic directional valve are mounted in the brake cylinder loop; a third electromagnetic directional valve and a fourth electromagnetic directional valve are mounted in the walking cylinder loop; a fifth electromagnetic directional valve and a sixth electromagnetic directional valve are mounted in the front expansion cylinder loop; a seventh electromagnetic directional valve and an eighth electromagnetic directional valve are mounted in the rear expansion cylinder loop; and a ninth electromagnetic directional valve and a tenth electromagnetic directional valve are mounted in the counterpart cylinder loop.

Description

Technical Field

[0001] The utility model relates to the technical field of internal welding machines, in particular to a hydraulic system of an internal welding machine. Background Art

[0002] At present, in the construction of long-distance pipelines, most of them need to use automatic welding equipment to automatically weld the pipelines, and the automatic welding construction process has been widely used in long-distance pipelines. In particular, the use of pipeline internal welding machines to automatically weld the pipelines has not only improved the welding quality, but also improved the welding efficiency, creating good conditions for the later pipeline maintenance and inspection. However, the existing pipeline internal welding machines use pneumatic systems as the driving system to achieve movement in the pipeline. However, the driving force provided by the pneumatic system is limited, and the climbing angle it adapts to is usually below 12°. When facing the large slope pipeline welding operation, the driving force of the pneumatic system is difficult to meet the operation requirements; and the use of the pneumatic system as a power source makes the structural size of the internal welding machine longer, and the bending ability in the pipeline is limited. The bending ability is ≥40D (D is the pipeline diameter), and it cannot adapt to pipelines with a small turning radius; in addition, the gas in the gas tank in the pneumatic system will be lost during the operation of the internal welding machine. After completing a welding, it is necessary to replenish the gas in the gas tank in time, which also increases the extra workload and reduces the welding efficiency. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a hydraulic system for an internal welding machine in view of the deficiencies in the prior art.

[0004] The technical solution of the utility model to solve the above technical problems is as follows: a hydraulic system of an internal welding machine, comprising: a hydraulic pump, a brake cylinder circuit, a travel cylinder circuit, a front expansion cylinder circuit, a rear expansion cylinder circuit, a counterpart cylinder circuit, a brake cylinder, a travel cylinder, a front expansion cylinder, a rear expansion cylinder, and a plurality of counterpart cylinders, the hydraulic pump is respectively connected to the brake cylinder circuit, the travel cylinder circuit, the front expansion cylinder circuit, the rear expansion cylinder circuit and the counterpart cylinder circuit; the brake cylinder circuit is connected to both ends of the brake cylinder, the travel cylinder circuit is connected to both ends of the travel cylinder, the front expansion cylinder circuit is connected to The two ends of the front expansion cylinder are connected, the rear expansion cylinder circuit is connected to the two ends of the rear expansion cylinder, and the counterpart cylinder circuit is respectively connected to multiple counterpart cylinders; the first solenoid reversing valve and the second solenoid reversing valve are installed in the brake cylinder circuit; the third solenoid reversing valve and the fourth solenoid reversing valve are installed in the travel cylinder circuit; the fifth solenoid reversing valve and the sixth solenoid reversing valve are installed in the front expansion cylinder circuit; the seventh solenoid reversing valve and the eighth solenoid reversing valve are installed in the rear expansion cylinder circuit; the ninth solenoid reversing valve and the tenth solenoid reversing valve are installed in the counterpart cylinder circuit.

[0005] The beneficial effects of the technical solution of the utility model are as follows: the hydraulic system of the internal welding machine can provide sufficient driving force, which can significantly improve the climbing ability of the internal welding machine, and thus meet the welding requirements of the internal welding machine for large-slope pipelines with a slope greater than 12°. The hydraulic system of the internal welding machine can reduce the length of the internal welding machine equipment, enhance the bending ability of the internal welding machine equipment, and meet the requirements of achieving bending and completing welding operations in pipelines <40D. The gas tank components in the pneumatic system are cancelled in the hydraulic system of the internal welding machine, and the process of inflating the gas tank after completing a welding operation is omitted, which reduces the workload of the welding operation and improves the efficiency of the welding operation. In normal operation, the electromagnetic reversing valves in the above five groups of main hydraulic circuits can be switched respectively to realize the extension and recovery operations of the brake cylinder, the travel cylinder, the front expansion cylinder, the rear expansion cylinder and the port cylinder, so as to control the internal welding machine to perform braking, travel, tightening, porting and positioning operations in the pipeline. It solves the technical problems existing in the prior art, such as insufficient driving force of the pneumatic system, insufficient bending ability caused by the long size, and reduced efficiency caused by inflating the gas tank.

[0006] Furthermore, it also includes: a first safety circuit and a second safety circuit, the first safety circuit is provided with an eleventh solenoid reversing valve and a twelfth solenoid reversing valve, the second safety circuit is provided with an eleventh solenoid reversing valve and a thirteenth solenoid reversing valve, the eleventh solenoid reversing valve is connected in a branch between the hydraulic pump and the rodless chamber of the brake cylinder, the twelfth solenoid reversing valve is connected in a pipeline between the first solenoid reversing valve and the rod chamber of the brake cylinder, the eleventh solenoid reversing valve is connected in a branch between the hydraulic pump and the rodless chamber of the travel cylinder, and the thirteenth solenoid reversing valve is connected in a pipeline between the third solenoid reversing valve and the rod chamber of the travel cylinder.

[0007] The beneficial effect of adopting the above further technical solution is that the safety circuit can be automatically enabled in special circumstances such as sudden power failure of the main circuit. After the safety circuit is started, the accumulator provides energy, and under the action of the electromagnetic reversing valve of the safety circuit, the travel cylinder and the brake cylinder are controlled to extend, so that the travel wheel and the brake extend and contact the inner wall of the steel pipe, ensuring that the equipment can stop immediately regardless of the state it is in, thereby ensuring the safety of the equipment and construction personnel. In normal operation, the electromagnetic reversing valves in the two sets of safety circuits are in a constant power state. When the main control system fails and cannot normally control the main circuit electromagnetic valve, or the internal welding machine slips and stalls, the safety control system will control the two sets of safety circuits to cut off the power of the electromagnetic reversing valves in the two sets of safety circuits, and the hydraulic oil can be pressurized in the rodless chambers of the brake cylinder and the travel cylinder respectively, so that the brake cylinder and the travel cylinder can be kept in the extended state, so that the internal welding machine can be stably positioned in the pipeline for braking to avoid slipping and stalling.

[0008] Furthermore, an accumulator is provided in each of the first safety circuit and the second safety circuit, and the accumulator is connected between the hydraulic pump and the eleventh electromagnetic reversing valve.

[0009] The beneficial effect of adopting the above-mentioned further technical solution is that when insufficient pressure occurs in the main hydraulic circuit and / or the safety circuit, or when abnormal conditions such as power failure occur in the main hydraulic circuit and / or the safety circuit, the accumulator can assist in pressurizing the pipeline, thereby keeping the brake cylinder and the travel cylinder in an extended state at all times, so that the internal welding machine maintains sufficient braking performance.

[0010] Furthermore, the first safety circuit and the second safety circuit are both connected to overflow valves.

[0011] The beneficial effect of adopting the above further technical solution is that the overflow valve is used to maintain the pressure in the system so that the pressure can be stable.

[0012] Furthermore, a plurality of the paired cylinders are arranged in parallel.

[0013] The beneficial effect of adopting the above-mentioned further technical scheme is as follows: the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the matching cylinder circuit and then passes through the tenth electromagnetic reversing valve, and then the rodless cavity of the matching cylinder is pressurized, and the three groups of matching cylinders can be extended to perform matching operations, so that the internal welding machine can be positioned in the center of the pipeline. After the matching is completed, the rear expansion cylinder can be extended to fix the part behind the cone head of the internal welding machine in the fixed pipe; the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the matching cylinder circuit and then passes through the ninth electromagnetic reversing valve, and then the rod cavity of the matching cylinder is pressurized, and the matching cylinder can be retracted, the movable pipe sleeve can be set on the cone head part of the internal welding machine, and then the front expansion cylinder is extended so that the front expansion boot supports the inner wall of the movable pipe and is concentric with the fixed pipe, and then the welding operation can be carried out.

[0014] Furthermore, the brake cylinder circuit and the travel cylinder circuit are both provided with a superimposed hydraulically controlled one-way valve and a superimposed one-way throttle valve. The superimposed hydraulically controlled one-way valve and the superimposed one-way throttle valve in the brake cylinder circuit are connected in the pipeline after the first solenoid reversing valve and the second solenoid reversing valve, and the superimposed hydraulically controlled one-way valve and the superimposed one-way throttle valve in the travel cylinder circuit are connected in the pipeline after the third solenoid reversing valve and the fourth solenoid reversing valve.

[0015] The beneficial effects of adopting the above further technical solution are: the superimposed one-way throttle valve in the brake cylinder circuit can adjust the circuit flow, thereby adjusting the action time of the brake cylinder; the superimposed hydraulic control one-way valve in the brake cylinder circuit can ensure that the brake cylinder does not move in special circumstances. The superimposed one-way throttle valve and superimposed pressure reducing valve in the travel cylinder circuit can adjust the circuit flow and pressure, thereby adjusting the action time and output of the travel cylinder; the superimposed hydraulic control one-way valve in the travel cylinder circuit can ensure that the travel cylinder does not move in special circumstances, thereby ensuring the safety of the equipment.

[0016] Furthermore, a superimposed pressure reducing valve and a pressure input pipeline are provided in the traveling cylinder circuit, and the superimposed pressure reducing valve is installed in the pressure input pipeline in the traveling cylinder circuit.

[0017] The beneficial effects of adopting the above-mentioned further technical scheme are: the superimposed one-way throttle valve and the superimposed pressure reducing valve in the walking cylinder circuit can adjust the circuit flow and pressure, thereby adjusting the action time and output size of the walking cylinder; the superimposed hydraulically controlled one-way valve in the walking cylinder circuit can ensure that the walking cylinder does not move unchanged under special circumstances, thereby ensuring the safety of the equipment.

[0018] Furthermore, both the front expansion cylinder circuit and the rear expansion cylinder circuit are provided with superimposed hydraulically controlled one-way valves. The superimposed hydraulically controlled one-way valve in the front expansion cylinder circuit is connected to the pipeline after the fifth solenoid reversing valve and the sixth solenoid reversing valve, and the superimposed hydraulically controlled one-way valve in the rear expansion cylinder circuit is connected to the pipeline after the seventh solenoid reversing valve and the eighth solenoid reversing valve.

[0019] The beneficial effect of adopting the above further technical solution is that the superimposed hydraulically controlled one-way valves in the front expansion cylinder circuit and the rear expansion cylinder circuit can ensure that the front expansion cylinder and the rear expansion cylinder do not move in special circumstances, thereby ensuring the safety of the equipment.

[0020] Furthermore, a pressure input pipeline, a superimposed pressure reducing valve and a superimposed throttle valve are provided in the counterpart cylinder circuit, and the superimposed pressure reducing valve and the superimposed throttle valve in the counterpart cylinder circuit are both connected to the pressure input pipeline of the counterpart cylinder circuit.

[0021] The beneficial effect of adopting the above further technical solution is that the superimposed pressure reducing valve and superimposed throttle valve in the matching cylinder circuit can adjust the circuit flow and pressure, thereby adjusting the action time and output size of the matching cylinder.

[0022] Further, the hydraulic pump is connected to a motor, the motor is connected to a controller, and the controller is respectively connected to the first solenoid reversing valve, the second solenoid reversing valve, the third solenoid reversing valve, the fourth solenoid reversing valve, the fifth solenoid reversing valve, the sixth solenoid reversing valve, the seventh solenoid reversing valve, the eighth solenoid reversing valve, the ninth solenoid reversing valve and the tenth solenoid reversing valve.

[0023] The beneficial effects of adopting the above further technical solution are: the motor is used to provide power for the hydraulic pump, and the controller is used to automatically control the working state of the electromagnetic reversing valve and the motor, thereby improving automation.

[0024] Advantages of additional aspects of the present invention will be partially given in the following description, and partially become apparent from the following description, or be understood through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic structural diagram of a hydraulic system of an internal welding machine provided in an embodiment of the utility model.

[0026] Explanation of the accompanying figures: 1. First solenoid reversing valve; 2. Second solenoid reversing valve; 3. Third solenoid reversing valve; 4. Fourth solenoid reversing valve; 5. Fifth solenoid reversing valve; 6. Sixth solenoid reversing valve; 7. Seventh solenoid reversing valve; 8. Eighth solenoid reversing valve; 9. Ninth solenoid reversing valve; 10. Tenth solenoid reversing valve; 11. Eleventh solenoid reversing valve; 12. Twelfth solenoid reversing valve; 13. Thirteenth solenoid reversing valve; 14. Hydraulic pump; 15. Brake cylinder Circuit; 16, travel cylinder circuit; 17, front expansion cylinder circuit; 18, rear expansion cylinder circuit; 19, counterpart cylinder circuit; 20, brake cylinder; 21, travel cylinder; 22, front expansion cylinder; 23, rear expansion cylinder; 24, counterpart cylinder; 25, first safety circuit; 26, second safety circuit; 27, accumulator; 28, relief valve; 29, superimposed hydraulically controlled one-way valve; 30, superimposed one-way throttle valve; 31, superimposed pressure reducing valve; 32, superimposed throttle valve; 33, motor. DETAILED DESCRIPTION

[0027] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The embodiments given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0028] like Figure 1 As shown, the embodiment of the utility model provides a hydraulic system of an internal welding machine, including: a hydraulic pump 14, a brake cylinder circuit 15, a travel cylinder circuit 16, a front expansion cylinder circuit 17, a rear expansion cylinder circuit 18, a counterpart cylinder circuit 19, a brake cylinder 20, a travel cylinder 21, a front expansion cylinder 22, a rear expansion cylinder 23, and a plurality of counterpart cylinders 24, wherein the hydraulic pump 14 is respectively connected to the brake cylinder circuit 15, the travel cylinder circuit 16, the front expansion cylinder circuit 17, the rear expansion cylinder circuit 18 and the counterpart cylinder circuit 19; the brake cylinder circuit 15 is connected to both ends of the brake cylinder 20, the travel cylinder circuit 16 is connected to both ends of the travel cylinder 21, and the front expansion cylinder circuit 17 is connected to both ends of the front expansion cylinder 22, the rear expansion cylinder circuit 18 is connected to both ends of the rear expansion cylinder 23, and the counterpart cylinder circuit 19 is respectively connected to multiple counterpart cylinders 24; the first electromagnetic reversing valve 1 and the second electromagnetic reversing valve 2 are installed in the brake cylinder circuit 15; the third electromagnetic reversing valve 3 and the fourth electromagnetic reversing valve 4 are installed in the travel cylinder circuit 16; the fifth electromagnetic reversing valve 5 and the sixth electromagnetic reversing valve 6 are installed in the front expansion cylinder circuit 17; the seventh electromagnetic reversing valve 7 and the eighth electromagnetic reversing valve 8 are installed in the rear expansion cylinder circuit 18; the ninth electromagnetic reversing valve 9 and the tenth electromagnetic reversing valve 10 are installed in the counterpart cylinder circuit 19.

[0029] The beneficial effects of the technical solution of the utility model are as follows: the hydraulic system of the internal welding machine can provide sufficient driving force, which can significantly improve the climbing ability of the internal welding machine, and thus meet the welding requirements of the internal welding machine for large-slope pipelines with a slope greater than 12°. The hydraulic system of the internal welding machine can reduce the length of the internal welding machine equipment, enhance the bending ability of the internal welding machine equipment, and meet the requirements of achieving bending and completing welding operations in pipelines <40D. The gas tank components in the pneumatic system are cancelled in the hydraulic system of the internal welding machine, and the process of inflating the gas tank after completing a welding operation is omitted, which reduces the workload of the welding operation and improves the efficiency of the welding operation. In normal operation, the electromagnetic reversing valves in the above five groups of main hydraulic circuits can be switched respectively to realize the extension and recovery operations of the brake cylinder, the travel cylinder, the front expansion cylinder, the rear expansion cylinder and the port cylinder, so as to control the internal welding machine to perform braking, travel, tightening, porting and positioning operations in the pipeline. It solves the technical problems existing in the prior art, such as insufficient driving force of the pneumatic system, insufficient bending ability caused by the long size, and reduced efficiency caused by inflating the gas tank.

[0030] Among them, the hydraulic pump can be connected to a hydraulic oil source.

[0031] It should be noted that the opening and closing control of the first solenoid reversing valve 1, the second solenoid reversing valve 2, the third solenoid reversing valve 3, the fourth solenoid reversing valve 4, the fifth solenoid reversing valve 5, the sixth solenoid reversing valve 6, the seventh solenoid reversing valve 7, the eighth solenoid reversing valve 8, the ninth solenoid reversing valve 9 and the tenth solenoid reversing valve 10 can all be manually controlled, and the user can design a controller according to actual needs to realize automatic control of the solenoid reversing valves.

[0032] The hydraulic system of the internal welding machine provided by the embodiment of the utility model includes: a brake cylinder circuit, a travel cylinder circuit, a front expansion cylinder circuit, a rear expansion cylinder circuit, a counterpart cylinder circuit and a safety circuit (a first safety circuit and a second safety circuit), wherein the brake cylinder circuit is connected to the two ends of the brake cylinder, and a first electromagnetic reversing valve 1 and a second electromagnetic reversing valve 2 are installed in the brake cylinder circuit; the travel cylinder circuit is connected to the two ends of the travel cylinder, and a third electromagnetic reversing valve 3 and a fourth electromagnetic reversing valve 4 are installed in the travel cylinder circuit; the front expansion cylinder circuit is connected to the two ends of the front expansion cylinder, and a fifth electromagnetic reversing valve 5 and a sixth electromagnetic reversing valve 6 are installed in the front expansion cylinder circuit; the rear expansion cylinder circuit is connected to the two ends of the rear expansion cylinder, and a seventh electromagnetic reversing valve 7 and an eighth electromagnetic reversing valve 8 are installed in the rear expansion cylinder circuit; the counterpart cylinder circuits are respectively connected to the two ends of the three groups of counterpart cylinders, and the three groups of counterpart cylinders are arranged in parallel with each other in the counterpart cylinder circuit, and a ninth electromagnetic reversing valve 9 and a tenth electromagnetic reversing valve 10 are installed in the counterpart cylinder circuit. During normal operation, the reversing valves in the above five groups of main hydraulic circuits can be switched respectively to realize the extension and retraction operations of the brake cylinder, travel cylinder, front expansion cylinder, rear expansion cylinder and mating cylinder, thereby controlling the internal welding machine to perform braking, travel, tightening, mating and positioning operations in the pipeline.

[0033] The safety circuit includes a first safety circuit and a second safety circuit. The first safety circuit includes an eleventh solenoid reversing valve 11 and a twelfth solenoid reversing valve 12, and the second safety circuit includes an eleventh solenoid reversing valve 11 and a thirteenth solenoid reversing valve 13. In normal operation, the solenoid reversing valves in the two safety circuits are in a normally energized state. When the main control system fails and cannot normally control the main circuit solenoid valve, or the internal welding machine slips and stalls, the safety control system will control the two safety circuits to cut off the power to the solenoid reversing valves in the two safety circuits. The hydraulic oil can be pressurized in the rodless chambers of the brake cylinder and the travel cylinder respectively, so that the brake cylinder and the travel cylinder can be kept in an extended state, so that the internal welding machine can be stably positioned in the pipeline for braking to avoid slipping and stalling.

[0034] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0035] 1. The hydraulic system of the internal welding machine of the utility model can provide sufficient driving force, which can significantly improve the climbing ability of the internal welding machine, thereby meeting the welding requirements of the internal welding machine for large-slope pipelines with a slope greater than 12°.

[0036] 2. The hydraulic system of the internal welding machine of the utility model can reduce the length of the internal welding machine equipment, enhance the bending ability of the internal welding machine equipment, and meet the needs of achieving bending and completing welding operations in pipes with a diameter of less than 40D.

[0037] 3. The hydraulic system of the internal welding machine of the utility model eliminates the gas tank component in the pneumatic system, and also omits the process of inflating the gas tank after completing a welding operation, thereby reducing the workload of the welding operation and improving the welding operation efficiency.

[0038] like Figure 1 As shown, it further includes: a first safety circuit 25 and a second safety circuit 26, the first safety circuit 25 is provided with an eleventh solenoid reversing valve 11 and a twelfth solenoid reversing valve 12, the second safety circuit 26 is provided with an eleventh solenoid reversing valve 11 and a thirteenth solenoid reversing valve 13, the eleventh solenoid reversing valve 11 is connected in a branch between the hydraulic pump 14 and the rodless chamber of the brake cylinder 20, the twelfth solenoid reversing valve 12 is connected in a pipeline between the first solenoid reversing valve 1 and the rod chamber of the brake cylinder 20, the eleventh solenoid reversing valve 11 is connected in a branch between the hydraulic pump 14 and the rodless chamber of the travel cylinder 21, and the thirteenth solenoid reversing valve 13 is connected in a pipeline between the third solenoid reversing valve 3 and the rod chamber of the travel cylinder 21.

[0039] The beneficial effect of adopting the above further technical solution is that the safety circuit can be automatically enabled in special circumstances such as sudden power failure of the main circuit. After the safety circuit is started, the accumulator provides energy, and under the action of the electromagnetic reversing valve of the safety circuit, the travel cylinder and the brake cylinder are controlled to extend, so that the travel wheel and the brake extend and contact the inner wall of the steel pipe, ensuring that the equipment can stop immediately regardless of the state it is in, thereby ensuring the safety of the equipment and construction personnel. In normal operation, the electromagnetic reversing valves in the two sets of safety circuits are in a constant power state. When the main control system fails and cannot normally control the main circuit electromagnetic valve, or the internal welding machine slips and stalls, the safety control system will control the two sets of safety circuits to cut off the power of the electromagnetic reversing valves in the two sets of safety circuits, and the hydraulic oil can be pressurized in the rodless chambers of the brake cylinder and the travel cylinder respectively, so that the brake cylinder and the travel cylinder can be kept in the extended state, so that the internal welding machine can be stably positioned in the pipeline for braking to avoid slipping and stalling.

[0040] like Figure 1 As shown, further, an accumulator 27 is provided in each of the first safety circuit 25 and the second safety circuit 26 , and the accumulator 27 is connected between the hydraulic pump 14 and the eleventh electromagnetic reversing valve 11 .

[0041] The beneficial effect of adopting the above-mentioned further technical solution is that when insufficient pressure occurs in the main hydraulic circuit and / or the safety circuit, or when abnormal conditions such as power failure occur in the main hydraulic circuit and / or the safety circuit, the accumulator can assist in pressurizing the pipeline, thereby keeping the brake cylinder and the travel cylinder in an extended state at all times, so that the internal welding machine maintains sufficient braking performance.

[0042] like Figure 1As shown, further, the first safety circuit 25 and the second safety circuit 26 are both connected to a relief valve 28 .

[0043] The beneficial effect of adopting the above further technical solution is that the overflow valve is used to maintain the pressure in the system so that the pressure can be stable.

[0044] like Figure 1 As shown, further, a plurality of the paired cylinders 24 are arranged in parallel.

[0045] The beneficial effect of adopting the above-mentioned further technical scheme is as follows: the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the matching cylinder circuit and then passes through the tenth electromagnetic reversing valve, and then the rodless cavity of the matching cylinder is pressurized, and the three groups of matching cylinders can be extended to perform matching operations, so that the internal welding machine can be positioned in the center of the pipeline. After the matching is completed, the rear expansion cylinder can be extended to fix the part behind the cone head of the internal welding machine in the fixed pipe; the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the matching cylinder circuit and then passes through the ninth electromagnetic reversing valve, and then the rod cavity of the matching cylinder is pressurized, and the matching cylinder can be retracted, the movable pipe sleeve can be set on the cone head part of the internal welding machine, and then the front expansion cylinder is extended so that the front expansion boot supports the inner wall of the movable pipe and is concentric with the fixed pipe, and then the welding operation can be carried out.

[0046] like Figure 1 As shown, further, the brake cylinder circuit 15 and the travel cylinder circuit 16 are both provided with a superimposed hydraulically controlled one-way valve 29 and a superimposed one-way throttle valve 30, the superimposed hydraulically controlled one-way valve and the superimposed one-way throttle valve in the brake cylinder circuit 15 are connected in the pipeline after the first solenoid reversing valve 1 and the second solenoid reversing valve 2, and the superimposed hydraulically controlled one-way valve and the superimposed one-way throttle valve in the travel cylinder circuit 16 are connected in the pipeline after the third solenoid reversing valve 3 and the fourth solenoid reversing valve 4.

[0047] The beneficial effects of adopting the above further technical solution are: the superimposed one-way throttle valve in the brake cylinder circuit can adjust the circuit flow, thereby adjusting the action time of the brake cylinder; the superimposed hydraulic control one-way valve in the brake cylinder circuit can ensure that the brake cylinder does not move in special circumstances. The superimposed one-way throttle valve and superimposed pressure reducing valve in the travel cylinder circuit can adjust the circuit flow and pressure, thereby adjusting the action time and output of the travel cylinder; the superimposed hydraulic control one-way valve in the travel cylinder circuit can ensure that the travel cylinder does not move in special circumstances, thereby ensuring the safety of the equipment.

[0048] like Figure 1 As shown, further, a superimposed pressure reducing valve 31 and a pressure input pipeline are provided in the travel cylinder circuit 16 , and the superimposed pressure reducing valve 31 is installed in the pressure input pipeline in the travel cylinder circuit 16 .

[0049] The beneficial effects of adopting the above-mentioned further technical scheme are: the superimposed one-way throttle valve and the superimposed pressure reducing valve in the walking cylinder circuit can adjust the circuit flow and pressure, thereby adjusting the action time and output size of the walking cylinder; the superimposed hydraulically controlled one-way valve in the walking cylinder circuit can ensure that the walking cylinder does not move unchanged under special circumstances, thereby ensuring the safety of the equipment.

[0050] like Figure 1 As shown, further, the front expansion cylinder circuit 17 and the rear expansion cylinder circuit 18 are both provided with superimposed hydraulically controlled one-way valves, the superimposed hydraulically controlled one-way valve in the front expansion cylinder circuit 17 is connected in the pipeline after the fifth solenoid reversing valve 5 and the sixth solenoid reversing valve 6, and the superimposed hydraulically controlled one-way valve in the rear expansion cylinder circuit 18 is connected in the pipeline after the seventh solenoid reversing valve 7 and the eighth solenoid reversing valve 8.

[0051] The beneficial effect of adopting the above further technical solution is that the superimposed hydraulically controlled one-way valves in the front expansion cylinder circuit and the rear expansion cylinder circuit can ensure that the front expansion cylinder and the rear expansion cylinder do not move in special circumstances, thereby ensuring the safety of the equipment.

[0052] like Figure 1 As shown, further, the counterpart cylinder circuit 19 is provided with a pressure input pipeline, a superimposed pressure reducing valve and a superimposed throttle valve 32, and the superimposed pressure reducing valve and the superimposed throttle valve 32 in the counterpart cylinder circuit 19 are both connected to the pressure input pipeline of the counterpart cylinder circuit 19.

[0053] The beneficial effect of adopting the above further technical solution is that the superimposed pressure reducing valve and superimposed throttle valve in the matching cylinder circuit can adjust the circuit flow and pressure, thereby adjusting the action time and output size of the matching cylinder.

[0054] like Figure 1 As shown, further, the hydraulic pump 14 is connected to a motor 33, the motor 33 is connected to a controller, and the controller is respectively connected to the first solenoid reversing valve 1, the second solenoid reversing valve 2, the third solenoid reversing valve 3, the fourth solenoid reversing valve 4, the fifth solenoid reversing valve 5, the sixth solenoid reversing valve 6, the seventh solenoid reversing valve 7, the eighth solenoid reversing valve 8, the ninth solenoid reversing valve 9 and the tenth solenoid reversing valve 10.

[0055] The beneficial effects of adopting the above further technical solution are: the motor is used to provide power for the hydraulic pump, and the controller is used to automatically control the working state of the electromagnetic reversing valve and the motor, thereby improving automation.

[0056] like Figure 1 As shown, the hydraulic system of the internal welding machine described in the embodiment of the utility model includes a brake cylinder circuit, a travel cylinder circuit, a front expansion cylinder circuit, a rear expansion cylinder circuit, a counterpart cylinder circuit and a safety circuit, wherein:

[0057] The brake cylinder circuit is connected to both ends of the brake cylinder. The first electromagnetic reversing valve 1 and the second electromagnetic reversing valve 2 are installed in the brake cylinder circuit. When the internal welding machine is braked, the second electromagnetic reversing valve 2 can be energized and the first electromagnetic reversing valve 1 can be de-energized. At this time, the pressure input pipeline of the brake cylinder circuit can be connected to the rodless chamber of the brake cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the brake cylinder circuit and can pass through the second electromagnetic reversing valve 2. Then, the rodless chamber of the brake cylinder is pressurized, and the brake cylinder can be extended. After the brake cylinder is extended, it represents that the internal welding machine is braked; when the brake needs to be released, the first electromagnetic reversing valve 1 can be energized and the second electromagnetic reversing valve 2 can be de-energized. At this time, the pressure input pipeline of the brake cylinder circuit can be connected to the rod chamber of the brake cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the brake cylinder circuit and can pass through the first electromagnetic reversing valve 1. Then, the rod chamber of the brake cylinder is pressurized, and the brake cylinder can be retracted. After the brake cylinder is retracted, it represents that the internal welding machine releases the brake and can move freely in the pipeline.

[0058] The travel cylinder circuit is connected to the two ends of the travel cylinder, and the third solenoid reversing valve 3 and the fourth solenoid reversing valve 4 are installed in the travel cylinder circuit. When it is necessary to drive the internal welding machine to move in the pipeline, the fourth solenoid reversing valve 4 can be energized, and the third solenoid reversing valve 3 can be de-energized. At this time, the pressure input pipeline of the travel cylinder circuit can be connected to the rodless cavity of the travel cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the travel cylinder circuit and can pass through the fourth solenoid reversing valve 4, and then pressurize the rodless cavity of the travel cylinder, so that the travel cylinder can be extended. After the travel cylinder is extended, it means that the travel driving wheel is extended and tightly supported on the inner wall of the pipeline, and the driving force can be provided to the travel driving wheel through the travel motor. On the one hand, it can prevent the internal welding machine from slipping in a pipeline with a large slope, and on the other hand, it can also provide sufficient driving force to drive the internal welding machine to climb a slope in a pipeline with a large slope; when the internal welding machine moves to the welding seam position and is fixed to the pipeline by the expansion shoe, the third electromagnetic reversing valve 3 can be energized, and the fourth electromagnetic reversing valve 4 can be de-energized. At this time, the pressure input pipeline of the walking cylinder circuit can be connected to the rod chamber of the walking cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the walking cylinder circuit and can pass through the third electromagnetic reversing valve 3, and then the rod chamber of the walking cylinder is pressurized, so that the walking cylinder can be retracted. After the walking cylinder is retracted, it means that the walking wheel can leave the inner wall of the pipeline, and the internal welding machine can be completely fixed by the expansion shoe.

[0059] The front expansion cylinder circuit is connected to the two ends of the front expansion cylinder, and the fifth solenoid reversing valve 5 and the sixth solenoid reversing valve 6 are installed in the front expansion cylinder circuit. When the internal welding machine reaches the pipeline welding position, the sixth solenoid reversing valve 6 can be energized, and the fifth solenoid reversing valve 5 can be de-energized. At this time, the pressure input pipeline of the front expansion cylinder circuit can be connected to the rodless chamber of the front expansion cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the front expansion cylinder circuit and can pass through the sixth solenoid reversing valve 6, and then pressurize the rodless chamber of the front expansion cylinder, so that the front expansion cylinder can be extended. After the front expansion cylinder is extended, it represents the front expansion shoe of the internal welding machine. By pressing against the inner wall of the pipeline and performing the tightening operation, the internal welding machine can be positioned in the pipeline; when the positioning needs to be released after welding, the fifth electromagnetic reversing valve 5 can be energized and the sixth electromagnetic reversing valve 6 can be de-energized. At this time, the pressure input pipeline of the front expansion cylinder circuit can be connected to the rod chamber of the front expansion cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the front expansion cylinder circuit and can pass through the fifth electromagnetic reversing valve 5, and then pressurize the rod chamber of the front expansion cylinder, so that the front expansion cylinder can be retracted. After the front expansion cylinder is retracted, it means that the front expansion boot has left the inner wall of the pipeline, which can release the constraint of the pipeline on the internal welding machine.

[0060] The rear expansion cylinder circuit is connected to the two ends of the rear expansion cylinder, and the seventh solenoid reversing valve 7 and the eighth solenoid reversing valve 8 are installed in the rear expansion cylinder circuit. When the internal welding machine reaches the pipeline welding position, the eighth solenoid reversing valve 8 can be energized, and the seventh solenoid reversing valve 7 can be de-energized. At this time, the pressure input pipeline of the rear expansion cylinder circuit can be connected to the rodless cavity of the rear expansion cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the rear expansion cylinder circuit and can pass through the eighth solenoid reversing valve 8, and then the rodless cavity of the rear expansion cylinder is pressurized, so that the rear expansion cylinder can be extended. After the rear expansion cylinder is extended, it represents the rear expansion boot of the internal welding machine. By pressing against the inner wall of the pipeline and performing the tightening operation, the internal welding machine can be positioned in the pipeline; when the positioning needs to be released after welding, the seventh electromagnetic reversing valve 7 can be energized and the eighth electromagnetic reversing valve 8 can be de-energized. At this time, the pressure input pipeline of the rear expansion cylinder circuit can be connected to the rod chamber of the rear expansion cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the rear expansion cylinder circuit and can pass through the seventh electromagnetic reversing valve 7, and then pressurize the rod chamber of the rear expansion cylinder, so that the rear expansion cylinder can be retracted. After the rear expansion cylinder is retracted, it means that the rear expansion boot has left the inner wall of the pipeline, which can release the constraint of the pipeline on the internal welding machine.

[0061] The matching cylinder circuits are respectively connected to the two ends of the three groups of matching cylinders, so that the three groups of matching cylinders are arranged in parallel with each other. The ninth solenoid reversing valve 9 and the tenth solenoid reversing valve 10 are installed in the matching cylinder circuit. When the internal welding machine needs matching operation, the tenth solenoid reversing valve 10 can be energized, and the ninth solenoid reversing valve 9 can be de-energized. At this time, the pressure input pipeline of the matching cylinder circuit can be connected to the rodless cavity of the matching cylinder. That is to say, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the matching cylinder circuit and can pass through the tenth solenoid reversing valve 10, and then pressurize the rodless cavity of the matching cylinder. The three groups of matching cylinders can be extended to perform matching operations, which can realize the positioning of the internal welding machine. In the center of the pipeline, after the docking is completed, the rear expansion cylinder can be extended to fix the part behind the cone head of the internal welding machine in the fixed pipe; then the ninth electromagnetic reversing valve 9 is energized, and the tenth electromagnetic reversing valve 10 is de-energized. At this time, the pressure input pipeline of the docking cylinder circuit can be connected to the rod chamber of the docking cylinder, that is, the hydraulic oil output from the hydraulic pump enters the pressure input pipeline of the docking cylinder circuit and can pass through the ninth electromagnetic reversing valve 9, and then the rod chamber of the docking cylinder is pressurized, the docking cylinder can be retracted, the movable tube can be set on the cone head part of the internal welding machine, and then the front expansion cylinder is extended so that the front expansion boot supports the inner wall of the movable tube and is concentric with the fixed tube, and then the welding operation can be carried out.

[0062] Furthermore, a superimposed hydraulically controlled one-way valve and a superimposed one-way throttle valve are also provided in the brake cylinder circuit and the travel cylinder circuit, wherein the superimposed hydraulically controlled one-way valve and the superimposed one-way throttle valve in the brake cylinder circuit are connected to the pipeline after the first electromagnetic reversing valve 1 and the second electromagnetic reversing valve 2, and the superimposed hydraulically controlled one-way valve and the superimposed one-way throttle valve in the travel cylinder circuit are connected to the pipeline after the third electromagnetic reversing valve 3 and the fourth electromagnetic reversing valve 4, and a superimposed pressure reducing valve is also provided in the travel cylinder circuit, and the superimposed pressure reducing valve is connected to the pressure input pipeline in the travel cylinder circuit;

[0063] The superimposed one-way throttle valve in the brake cylinder circuit can adjust the circuit flow, thereby adjusting the action time of the brake cylinder; the superimposed hydraulically controlled one-way valve in the brake cylinder circuit can ensure that the brake cylinder does not change its action under special circumstances.

[0064] The superimposed one-way throttle valve and superimposed pressure reducing valve in the travel cylinder circuit can adjust the circuit flow and pressure, thereby adjusting the action time and output of the travel cylinder; the superimposed hydraulically controlled one-way valve in the travel cylinder circuit can ensure that the travel cylinder does not move unchanged under special circumstances, thereby ensuring the safety of the equipment.

[0065] Furthermore, superimposed hydraulically controlled one-way valves are respectively provided in the front expansion cylinder circuit and the rear expansion cylinder circuit, wherein the superimposed hydraulically controlled one-way valve in the front expansion cylinder circuit is connected to the pipeline after the fifth solenoid reversing valve 5 and the sixth solenoid reversing valve 6, and the superimposed hydraulically controlled one-way valve in the rear expansion cylinder circuit is connected to the pipeline after the seventh solenoid reversing valve 7 and the eighth solenoid reversing valve 8.

[0066] The superimposed hydraulically controlled one-way valves in the front expansion cylinder circuit and the rear expansion cylinder circuit can ensure that the front expansion cylinder and the rear expansion cylinder remain in motion under special circumstances, thereby ensuring the safety of the equipment.

[0067] Furthermore, a superimposed pressure reducing valve and a superimposed throttle valve are also provided in the counterpart cylinder circuit, and the superimposed pressure reducing valve and the superimposed throttle valve are both connected to the pressure input pipeline of the counterpart cylinder circuit; the superimposed pressure reducing valve and the superimposed throttle valve in the counterpart cylinder circuit can adjust the circuit flow and pressure, thereby adjusting the action time and output size of the counterpart cylinder.

[0068] The safety circuit can be automatically activated in special circumstances such as sudden power failure of the main circuit. After the safety circuit is activated, the accumulator provides energy, and under the action of the electromagnetic reversing valve of the safety circuit, the travel cylinder and brake cylinder are controlled to extend, so that the travel wheel and brake extend and contact the inner wall of the steel pipe, ensuring that the equipment can stop immediately no matter what state it is in, thereby ensuring the safety of the equipment and construction personnel. The working principle of the safety circuit is described in detail as follows:

[0069] The safety circuit may include a first safety circuit and a second safety circuit; wherein:

[0070] The first safety circuit includes an eleventh solenoid reversing valve 11 and a twelfth solenoid reversing valve 12. The eleventh solenoid reversing valve 11 is connected to the branch between the hydraulic pump and the rodless chamber of the brake cylinder, and the twelfth solenoid reversing valve 12 is connected to the pipeline between the first solenoid reversing valve 1 and the rod chamber of the brake cylinder. When the internal welding machine does not slip and stall during operation, the first safety circuit is not started, the eleventh solenoid reversing valve 11 is always powered and is in a disconnected state, and the twelfth solenoid reversing valve 12 is always powered and is in a conducting state. At this time, the hydraulic oil output from the hydraulic pump does not pass through the eleventh solenoid reversing valve 11, and enters the first main hydraulic circuit. It can pass through the first solenoid reversing valve 1 and can optionally pass through the twelfth solenoid reversing valve 12 and be input into the rod chamber of the brake cylinder to close the brake cylinder. Release the brake; when the main control system fails and cannot control the main circuit solenoid valve normally, or the internal welding machine slips and stalls, the safety control system will control the two groups of safety circuits to cut off the power to the solenoid reversing valves in the two groups of safety circuits. Specifically, the electrical control unit (controller) controls the first safety circuit to start, the eleventh solenoid reversing valve 11 is de-energized and turned on, and the twelfth solenoid reversing valve 12 is de-energized and disconnected. At this time, the hydraulic oil output from the hydraulic pump can enter the branch through the eleventh solenoid reversing valve 11 to pressurize the rodless chamber of the brake cylinder. At the same time, the first main hydraulic circuit is disconnected due to the disconnection of the twelfth solenoid reversing valve 12, and the hydraulic oil cannot pressurize the rod chamber of the brake cylinder, so that the brake cylinder can always remain extended, and the internal welding machine also remains in the braking state to prevent slipping.

[0071] The second safety circuit includes an eleventh solenoid reversing valve 11 and a thirteenth solenoid reversing valve 13. The eleventh solenoid reversing valve 11 is connected to a branch between the hydraulic pump and the rodless chamber of the travel cylinder, and the thirteenth solenoid reversing valve 13 is connected to a pipeline between the third solenoid reversing valve 3 and the rod chamber of the travel cylinder. When the internal welding machine does not slip or stall during operation, the second safety circuit is not started, the eleventh solenoid reversing valve 11 is always powered and is in a disconnected state, and the thirteenth solenoid reversing valve 13 is always powered and is in a conducting state. At this time, the hydraulic oil output from the hydraulic pump does not pass through the eleventh solenoid reversing valve 11, and can enter the second main hydraulic circuit through the third solenoid reversing valve 3 and can choose to pass through the thirteenth solenoid reversing valve 13 and The input into the rod chamber of the travel cylinder causes the travel cylinder to be retracted and the travel driving wheel to leave the inner wall of the pipe; when the internal welding machine slips and stalls during operation, the electrical control unit controls the start-up of the second safety circuit, the eleventh solenoid reversing valve 11 is powered off and turned on, and the thirteenth solenoid reversing valve 13 is powered off and disconnected. At this time, the hydraulic oil output from the hydraulic pump can enter the branch through the eleventh solenoid reversing valve 11 to pressurize the rodless chamber of the travel cylinder. At the same time, the second main hydraulic circuit is disconnected due to the disconnection of the thirteenth solenoid reversing valve 13, and the hydraulic oil cannot pressurize the rod chamber of the travel cylinder, so that the travel cylinder can always remain extended and the travel driving wheel can be pressed against the inner wall of the pipe, and the travel motor can be used to provide driving force to prevent slipping.

[0072] Furthermore, accumulators are provided in both the first safety circuit and the second safety circuit. The accumulators can be connected between the hydraulic pump and the eleventh solenoid reversing valve 11. When insufficient pressure occurs in the main hydraulic circuit and / or the safety circuit, or when power failure or other abnormal conditions occur in the main hydraulic circuit and / or the safety circuit, the accumulators can assist in pressurizing the pipeline, thereby keeping the brake cylinder and the travel cylinder in an extended state at all times, so that the internal welding machine maintains sufficient braking performance.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A hydraulic system for an internal welding machine, characterized in that: include: A hydraulic pump, a brake cylinder circuit, a travel cylinder circuit, a front expansion cylinder circuit, a rear expansion cylinder circuit, a counterpart cylinder circuit, a brake cylinder, a travel cylinder, a front expansion cylinder, a rear expansion cylinder, and a plurality of counterpart cylinders, wherein the hydraulic pump is respectively connected to the brake cylinder circuit, the travel cylinder circuit, the front expansion cylinder circuit, the rear expansion cylinder circuit, and the counterpart cylinder circuit; the brake cylinder circuit is connected to both ends of the brake cylinder, the travel cylinder circuit is connected to both ends of the travel cylinder, the front expansion cylinder circuit is connected to both ends of the front expansion cylinder, the rear expansion cylinder circuit is connected to both ends of the rear expansion cylinder, and the counterpart cylinder circuit is respectively connected to a plurality of the counterpart cylinders; a first solenoid reversing valve and a second solenoid reversing valve are installed in the brake cylinder circuit; a third solenoid reversing valve and a fourth solenoid reversing valve are installed in the travel cylinder circuit; a fifth solenoid reversing valve and a sixth solenoid reversing valve are installed in the front expansion cylinder circuit; a seventh solenoid reversing valve and an eighth solenoid reversing valve are installed in the rear expansion cylinder circuit; and a ninth solenoid reversing valve and a tenth solenoid reversing valve are installed in the counterpart cylinder circuit.

2. The hydraulic system of an internal welding machine according to claim 1, characterized in that: Also includes: A first safety circuit and a second safety circuit, wherein the first safety circuit is provided with an eleventh solenoid reversing valve and a twelfth solenoid reversing valve, and the second safety circuit is provided with an eleventh solenoid reversing valve and a thirteenth solenoid reversing valve, the eleventh solenoid reversing valve is connected in a branch between the hydraulic pump and the rodless chamber of the brake cylinder, the twelfth solenoid reversing valve is connected in a pipeline between the first solenoid reversing valve and the rod chamber of the brake cylinder, the eleventh solenoid reversing valve is connected in a branch between the hydraulic pump and the rodless chamber of the travel cylinder, and the thirteenth solenoid reversing valve is connected in a pipeline between the third solenoid reversing valve and the rod chamber of the travel cylinder.

3. The hydraulic system of an internal welding machine according to claim 2, characterized in that: The first safety circuit and the second safety circuit are both provided with accumulators, and the accumulators are connected between the hydraulic pump and the eleventh electromagnetic reversing valve.

4. The hydraulic system of an internal welding machine according to claim 2, characterized in that: The first safety circuit and the second safety circuit are both connected to overflow valves.

5. The hydraulic system of an internal welding machine according to claim 1, characterized in that: A plurality of the paired cylinders are arranged in parallel.

6. The hydraulic system of an internal welding machine according to claim 1, characterized in that: The brake cylinder circuit and the travel cylinder circuit are both provided with a superimposed hydraulically controlled one-way valve and a superimposed one-way throttle valve. The superimposed hydraulically controlled one-way valve and the superimposed one-way throttle valve in the brake cylinder circuit are connected in the pipeline after the first solenoid reversing valve and the second solenoid reversing valve, and the superimposed hydraulically controlled one-way valve and the superimposed one-way throttle valve in the travel cylinder circuit are connected in the pipeline after the third solenoid reversing valve and the fourth solenoid reversing valve.

7. The hydraulic system of an internal welding machine according to claim 6, characterized in that: A superimposed pressure reducing valve and a pressure input pipeline are provided in the traveling cylinder circuit, and the superimposed pressure reducing valve is installed in the pressure input pipeline in the traveling cylinder circuit.

8. The hydraulic system of an internal welding machine according to claim 1, characterized in that: The front expansion cylinder circuit and the rear expansion cylinder circuit are both provided with superimposed hydraulically controlled one-way valves. The superimposed hydraulically controlled one-way valve in the front expansion cylinder circuit is connected to the pipeline after the fifth solenoid reversing valve and the sixth solenoid reversing valve, and the superimposed hydraulically controlled one-way valve in the rear expansion cylinder circuit is connected to the pipeline after the seventh solenoid reversing valve and the eighth solenoid reversing valve.

9. The hydraulic system of an internal welding machine according to claim 1, characterized in that: The paired cylinder circuit is provided with a pressure input pipeline, a superimposed pressure reducing valve and a superimposed throttle valve. The superimposed pressure reducing valve and the superimposed throttle valve in the paired cylinder circuit are both connected to the pressure input pipeline of the paired cylinder circuit.

10. The hydraulic system of an internal welding machine according to claim 1, characterized in that: The hydraulic pump is connected to a motor, the motor is connected to a controller, and the controller is respectively connected to the first solenoid reversing valve, the second solenoid reversing valve, the third solenoid reversing valve, the fourth solenoid reversing valve, the fifth solenoid reversing valve, the sixth solenoid reversing valve, the seventh solenoid reversing valve, the eighth solenoid reversing valve, the ninth solenoid reversing valve and the tenth solenoid reversing valve.

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