Hydraulic feeding device and control method thereof

Abstract

The application discloses a hydraulic feeding device and a control method thereof. The hydraulic feeding device comprises a variable-diameter hydraulic cylinder, a working system, a fast pushing system, a slow pushing system and an auxiliary system. The variable-diameter hydraulic cylinder comprises a large-diameter hydraulic cylinder, a variable-diameter piston and a small-diameter hydraulic cylinder. The large-diameter hydraulic cylinder and the small-diameter hydraulic cylinder are coaxially arranged oppositely. The variable-diameter piston comprises a middle piston rod and piston heads at two ends which are matched with the large-diameter hydraulic cylinder and the small-diameter hydraulic cylinder respectively. The piston heads are arranged in the large-diameter hydraulic cylinder and the small-diameter hydraulic cylinder respectively. The variable-diameter piston is pushed by supplying liquid to the large-diameter hydraulic cylinder, and then the small-diameter hydraulic cylinder is pushed, so that the displacement is reduced and the feeding pressure is increased. The application has simple structure and adopts indirect driving mode. The slow hydraulic pump pushes the piston in the large-diameter hydraulic cylinder, and then pushes the small-diameter hydraulic cylinder to supply liquid. Due to the change of the cross-sectional area of the two ends of the variable-diameter piston, the purpose of higher pushing pressure under small displacement is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of hydraulic control, and relates to a hydraulic feeding device and a control method thereof. BACKGROUND

[0002] The underbalanced operation technology has irreplaceable technical advantages and has become a main engineering technical means for improving and stabilizing single well production. However, due to the fact that the production pipe string is in a complex environment in the well for a long time, the threaded connection of the pipe string is often rusted, and the normal unthreading cannot be realized, so that the whole underbalanced pipe string operation cannot be realized. In order to normally carry out the underbalanced operation, the oil pipe must be sealed and cut. When the underbalanced cutting tool cuts the pipe string, it needs to meet the requirements of smooth cutting and easy lifting of the pipe string, so the feeding needs to be low-speed and smooth, and the thrust needs to be sufficient.

[0003] The utility model patent with the patent publication number CN203018823U discloses an underbalanced operation cutting tool, which works with the underbalanced operation machine, can cut the complex pipe string under pressure, and can be lifted in sections to ensure the smooth implementation of the underbalanced operation. The cutter of the device is installed on the feeding hydraulic cylinder inside the cutting cavity, the feeding hydraulic cylinder is installed on the rotating seat, the rotating seat is connected with the driving shaft through the gear, and when in use, the cutter rotates with the rotating seat under the driving of the driving shaft, and the pressure difference between the oil injection port and the cutting cavity interface is controlled to make the cutter head move radially to realize the feeding, and then the cutting operation is completed.

[0004] However, the patent uses a variable frequency motor to drive an electric cylinder to push the hydraulic cylinder to realize the feeding, but due to the characteristics of the variable frequency motor, the torque decreases at low frequency, which makes it difficult to realize the purpose of low-speed and smooth cutting.

[0005] The utility model patent with the patent publication number CN216589413U discloses a high-low pressure feeding hydraulic control system, which belongs to the field of hydraulic control technology and comprises a low-pressure flow pump and a high-pressure flow pump. The liquid inlet port of the low-pressure flow pump is fixedly connected with a first liquid inlet pipe, the liquid outlet port of the low-pressure flow pump is fixedly connected with a first circulating pipe, one end of the first circulating pipe away from the low-pressure flow pump is fixedly connected inside a first oil cylinder, and the liquid inlet port of the high-pressure flow pump is fixedly connected with a second liquid inlet pipe.

[0006] The patent uses the high-pressure flow pump to provide high pressure for the hydraulic system, but the high-pressure flow pump has the problems of unstable flow, larger size than the centrifugal pump under the same flow, complex mechanism, large amount of funds, difficult maintenance, etc.

[0007] Therefore, there is an urgent need for a hydraulic propulsion device with adjustable feeding speed, which still has high propulsion pressure in the state of micro-feeding and can be applied to other similar working conditions requiring small displacement and high pressure propulsion. SUMMARY

[0008] The present application aims to solve the problem that the torque of a variable frequency motor is small in the low frequency state, the propulsion pressure is insufficient, and it is difficult to achieve micro-feeding at high pressure, resulting in that the cutting tool cannot complete stable cutting at low speed under pressure operation. The present application provides a hydraulic feeding device and a control method thereof, which has the characteristics of high pressure in small displacement working condition, large displacement adjustment range, and convenient use.

[0009] In order to achieve the above-mentioned application purposes, the technical solutions of the present application are as follows:

[0010] A hydraulic feeding device, comprising

[0011] A variable diameter hydraulic cylinder, the variable diameter hydraulic cylinder comprises a large diameter hydraulic cylinder, a variable diameter piston and a small diameter hydraulic cylinder, the large diameter hydraulic cylinder and the small diameter hydraulic cylinder are coaxially arranged opposite to each other, the variable diameter piston comprises a middle piston rod and two piston heads at both ends which are matched with the large diameter hydraulic cylinder and the small diameter hydraulic cylinder respectively, the piston heads are arranged in the large diameter hydraulic cylinder and the small diameter hydraulic cylinder respectively, the variable diameter piston is pushed by supplying liquid to the large diameter hydraulic cylinder, and the small diameter hydraulic cylinder is pushed by the variable diameter piston, so as to realize reducing displacement and increasing feeding pressure at the same time;

[0012] A working system, the working system comprises an oil inlet on-off valve, a check valve, a working hydraulic cylinder, an oil return on-off valve and an oil return speed regulating valve, one end of the oil inlet on-off valve is connected with the oil outlet of the small diameter hydraulic cylinder through a hydraulic pipeline, the other end of the oil inlet on-off valve is connected with the oil inlet of the check valve, the oil outlet of the check valve is connected with the oil inlet of the rodless cavity of the working hydraulic cylinder, the oil outlet of the rodless cavity of the working hydraulic cylinder is sequentially connected with the oil return on-off valve, the oil return speed regulating valve and a hydraulic oil tank, the working hydraulic cylinder comprises a pushing cylinder position and a retracting cylinder position; the working system is suitable for various working conditions requiring hydraulic propulsion, and is especially suitable for working conditions requiring small displacement and high pressure, such as the cutting tool cutting pipe column under pressure operation, which needs to meet the requirements of flat cut and easy to lift the pipe column again, so the cutting tool needs low speed and stable feeding and sufficient thrust; the working hydraulic cylinder is the final execution device of the system, which can be flexibly arranged according to the actual working condition, and is connected to a slow propulsion system and a fast propulsion system through a hydraulic pipeline to realize different propulsion speeds.

[0013] A fast propulsion system, the fast propulsion system comprises a fast feeding stop valve, a fast feeding hydraulic pump and a fast feeding pump on-off valve, the oil outlet of the fast feeding hydraulic pump, the fast feeding pump on-off valve, the fast feeding stop valve and the oil outlet of the small diameter hydraulic cylinder are sequentially connected through a hydraulic pipeline, a three-way pipe is arranged on the hydraulic pipeline between the fast feeding pump on-off valve and the fast feeding stop valve, and the three-way pipe is connected to the oil outlet of the large diameter hydraulic cylinder through a hydraulic pipeline; the fast propulsion system can realize fast pushing of the working hydraulic cylinder or fast retracting of the variable diameter piston;

[0014] The slow propulsion system comprises a slow hydraulic pump and a slow reversing valve, the slow hydraulic pump outlet, the slow reversing valve are connected through a hydraulic pipeline, the slow reversing valve outlet pipeline is respectively connected to the large-diameter cylinder inlet and outlet, the slow hydraulic pump selects a hydraulic pump with smaller displacement than the fast hydraulic pump, and a variable frequency motor is selected as the power source, and the hydraulic pump displacement can be further adjusted by frequency modulation;

[0015] The auxiliary system comprises a hydraulic oil tank, which is connected with the slow reversing valve return oil port, the slow hydraulic pump inlet and the fast hydraulic pump inlet through hydraulic pipelines respectively.

[0016] Further, the variable-diameter cylinder is also provided with a displacement scale, which is arranged at the end position of the large-diameter cylinder on the side of the variable-diameter piston, for real-time monitoring of the position of the variable-diameter piston, to prevent the piston from reaching the end of the cylinder.

[0017] Further, a visual exhaust device is arranged between the oil return on-off valve of the working system and the hydraulic oil tank, and the emergence of air bubbles in the return oil can be observed through the glass window of the visual exhaust device to determine whether air enters and exhaust the gas in the working cylinder.

[0018] Further, an oil return pressure sensor is arranged between the working cylinder rodless cavity outlet of the working system and the oil return on-off valve.

[0019] Further, a fast forward pressure gauge and a fast forward overflow valve are installed in the pipeline between the fast forward hydraulic pump outlet of the fast forward propulsion system and the hydraulic oil tank, and the fast forward overflow valve can ensure that the pump outlet hydraulic pipeline is safe and not overpressure when the fast forward hydraulic pump is mistakenly opened without opening the fast forward pump on-off valve.

[0020] Further, an oil inlet pressure sensor and a safety overflow valve are arranged in the pipeline between the fast forward cut-off valve of the fast forward propulsion system and the small-diameter cylinder outlet, and the safety overflow valve can ensure that the working system and the hydraulic pipeline are safe and not overpressure by adjusting the overflow value of the safety overflow valve.

[0021] Further, a slow forward pressure gauge and a slow forward overflow valve are installed at the slow forward hydraulic pump outlet, and the slow forward overflow valve can ensure that the pump outlet hydraulic pipeline is safe and not overpressure when the fast forward hydraulic pump is mistakenly opened without opening the fast forward pump on-off valve.

[0022] Further, the visual exhaust device, the safety overflow valve, the fast forward overflow valve, the slow forward reversing valve and the slow forward overflow valve are installed on the upper cover of the hydraulic oil tank, which is convenient for oil return and reduces the space occupation of the device.

[0023] The slow hydraulic pump is matched with a variable frequency motor (BM) to further fine-tune the propulsion speed in the slow propulsion state.

[0024] A control method of a hydraulic feeding device, comprising the following five working states, namely slow advancing state, fast advancing state, fast returning variable diameter piston state, slow returning variable diameter piston state and circulating exhaust state.

[0025] The slow advancing state control steps are as follows:

[0026] 1) Turn on the power supply of the device;

[0027] 2) Adjust the slow advancing directional valve to the cylinder pushing position;

[0028] 3) Turn on the oil inlet on-off valve;

[0029] 4) Turn off the fast advancing pump on-off valve, the fast advancing stop valve and the oil return on-off valve respectively;

[0030] 5) After checking the correct valve position, turn on the slow advancing hydraulic pump to start the slow advancing work of the cylinder;

[0031] 6) Further adjust the advancing speed in the slow advancing state by adjusting the frequency of the frequency conversion motor matched with the slow advancing hydraulic pump.

[0032] The fast advancing state control steps are as follows:

[0033] 1) Turn on the power supply of the device;

[0034] 2) Adjust the slow advancing directional valve to the middle position;

[0035] 3) Turn on the fast advancing pump on-off valve, the fast advancing stop valve and the oil inlet on-off valve respectively;

[0036] 4) Turn off the oil return on-off valve;

[0037] 5) After checking the correct valve position, turn on the fast advancing hydraulic pump to start the fast advancing work of the cylinder.

[0038] The fast returning variable diameter piston state control steps are as follows:

[0039] 1) When the variable diameter piston in the variable diameter cylinder travels to the right end, its stroke is finished, and the variable diameter piston 1.2 needs to be returned to the left end to advance again;

[0040] 2) Turn on the power supply of the device and adjust the slow advancing directional valve to the middle position;

[0041] 3) Turn on the fast advancing pump on-off valve and the fast advancing stop valve respectively;

[0042] 4) Turn off the oil inlet on-off valve and the oil return on-off valve respectively;

[0043] 5) After checking the correct valve position, turn on the fast advancing hydraulic pump to start the fast returning variable diameter piston, and stop when it is pushed to the left end.

[0044] The slow retraction variable-diameter piston state control steps are as follows:

[0045] 1) When the variable-diameter piston in the variable-diameter cylinder travels to the right end, retraction is started;

[0046] 2) The device power supply is turned on, and the slow advance directional control valve is adjusted to the retraction position;

[0047] 3) The fast advance shut-off valve is opened;

[0048] 4) The oil inlet on-off valve, the oil return on-off valve and the fast advance pump on-off valve are closed respectively;

[0049] 5) After checking that the valve positions are correct, the slow advance hydraulic pump is started to slowly retract the variable-diameter piston, until it is pushed to the left end and stopped.

[0050] The circulating exhaust state control steps are as follows:

[0051] 1) When the working cylinder is used for the first time, is not used for a long time or other conditions are judged to have bubbles inside, it should be circulated and exhausted;

[0052] 2) The device power supply is turned on, and the slow advance directional control valve is adjusted to the neutral position;

[0053] 3) The fast advance pump on-off valve, the fast advance shut-off valve, the oil inlet on-off valve and the oil return on-off valve are opened respectively;

[0054] 4) After checking that the valve positions are correct, the fast advance hydraulic pump is started to circulate and exhaust;

[0055] 5) During the circulation, the oil return state displayed on the glass window of the visual exhaust device is observed;

[0056] 6) After observing that there are no bubbles on the glass window of the visual exhaust device, the exhaust is stopped;

[0057] 7) After standing for 30 minutes, the above steps are repeated to circulate and exhaust until no bubbles are emitted in the oil return.

[0058] The beneficial effects of the present application are:

[0059] 1. The present application has a simple structure, adopts an indirect driving form, a slow hydraulic pump pushes a piston in a large-diameter cylinder, and then pushes a small-diameter cylinder for liquid supply. Due to the change of the cross-sectional area of the two ends of the variable-diameter piston, the purpose of higher pushing pressure under small displacement is achieved. The problem of insufficient pushing pressure and difficulty in realizing high-pressure micro-feeding caused by the decrease of torque in the low-frequency state of the variable-frequency motor directly driven is avoided.

[0060] 2. In the application, by changing the different propulsion systems in the system, fast and slow propulsion speeds can be achieved, and by adjusting the speed of the variable frequency motor in the slow propulsion system, further fine tuning of the propulsion speed can be achieved, which can be used in various working conditions.

[0061] 3. In the application, the working cylinder is connected with other parts of the system through hydraulic pipelines. In actual application, the devices in the system can be arranged at different positions according to specific working conditions, and hydraulic pipelines of different lengths are selected for connection, which has the characteristics of flexible layout and strong applicability.

[0062] 4. In the application, an overflow valve is arranged at the outlet of each pump, and a safety overflow valve is arranged at the high-pressure end of the outlet of the variable-diameter cylinder, which can protect the pipelines, joints and the like in the system and is safe and reliable to use.

[0063] 5. In the application, by changing the different propulsion systems in the system, fast and slow speeds can be achieved for retraction, and when the fast retraction fails to be achieved, the slow retraction can be used to retract the piston of the variable-diameter cylinder. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 It is a structure schematic view of the hydraulic feeding device of the application.

[0065] Figure 2 It is a structure schematic view of the hydraulic feeding device in slow propulsion state of the application.

[0066] Figure 3 It is a structure schematic view of the hydraulic feeding device in fast propulsion state of the application.

[0067] Figure 4 It is a structure schematic view of the hydraulic feeding device in fast retraction state of the application.

[0068] Figure 5 It is a structure schematic view of the hydraulic feeding device in slow retraction state of the application.

[0069] Figure 6 It is a structure schematic view of the hydraulic feeding device in slow retraction state of the application.

[0070] Wherein, 1, variable diameter cylinder; 2, working system; 3, fast propulsion system; 4, slow propulsion system; 5, auxiliary system; 1.1, large diameter cylinder; 1.2, variable diameter piston; 1.3, displacement scale; 1.4, small diameter cylinder; 2.1, oil inlet on-off valve; 2.2, check valve; 2.3, working cylinder; 2.4, oil return pressure sensor; 2.5, oil return on-off valve; 2.6, oil return speed regulating valve; 2.7, visual exhaust device; 3.1, oil inlet pressure sensor; 3.2, safety overflow valve; 3.3, fast inlet stop valve; 3.4, fast inlet pressure gauge; 3.5, fast inlet overflow valve; 3.6, fast inlet hydraulic pump; 3.7, fast inlet pump on-off valve; 4.1, slow inlet hydraulic pump; 4.2, slow inlet reversing valve; 4.3, slow inlet overflow valve; 4.4, slow inlet pressure gauge; 5.1, hydraulic oil tank; 5.2, hydraulic pipeline. DETAILED DESCRIPTION

[0071] In order to further understand the present application, the specific implementation method of the present application is described below in combination with examples.

[0072] It should be noted that the structures, proportions, sizes, etc. shown in the present specification are only used to cooperate with the content disclosed in the specification for understanding and reading by those skilled in the art, and are not used to limit the implementation conditions of the present application. Any modification of structure, change of proportion relationship or adjustment of size, which does not affect the effects and purposes that can be achieved by the present application, should be within the scope of the technical content disclosed by the present application.

[0073] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" referred to in the present specification are only for the convenience of clear description, and are not used to limit the implementation range of the present application. The change or adjustment of relative relationship, without substantial change of technical content, is also regarded as the implementation scope of the present application.

[0074] Example 1

[0075] As Figure 1 , 2As shown in FIGS. 1-5, a hydraulic feeding device comprises a variable-diameter hydraulic cylinder 1, a working system 2, a fast advancing system 3, a slow advancing system 4 and an auxiliary system 5. The variable-diameter hydraulic cylinder 1 comprises a large-diameter hydraulic cylinder 1.1, a variable-diameter piston 1.2 and a small-diameter hydraulic cylinder 1.4. The large-diameter hydraulic cylinder 1.1 is coaxially arranged opposite to the small-diameter hydraulic cylinder 1.4. The variable-diameter piston 1.2 comprises a middle piston rod and two piston heads at two ends respectively matched with the large-diameter hydraulic cylinder 1.1 and the small-diameter hydraulic cylinder 1.4. The piston heads are arranged in the large-diameter hydraulic cylinder 1.1 and the small-diameter hydraulic cylinder 1.4 respectively. The variable-diameter piston 1.2 is pushed by supplying liquid to the large-diameter hydraulic cylinder 1.1, and then the small-diameter hydraulic cylinder 1.4 is pushed by the variable-diameter piston 1.2, so as to achieve the purpose of reducing the displacement and increasing the feeding pressure. The working system 2 comprises an oil inlet and outlet valve 2.1, a working hydraulic cylinder 2.3 and an oil return valve 2.5. The oil inlet and outlet valve 2.1 is connected with the small-diameter hydraulic cylinder 1.4 oil outlet through a hydraulic pipeline 5.2 at one end, and connected with the working hydraulic cylinder 2.3 no-rod cavity oil inlet at the other end. The working hydraulic cylinder 2.3 no-rod cavity oil outlet is connected with the oil return valve 2.5. The working hydraulic cylinder 2.3 comprises a pushing cylinder position and a cylinder retraction position. The fast advancing system 3 comprises a fast advance stop valve 3.3, a fast advance hydraulic pump 3.6 and a fast advance pump on-off valve 3.7. The fast advance hydraulic pump 3.6 oil outlet, the fast advance pump on-off valve 3.7, the fast advance stop valve 3.3 and the small-diameter hydraulic cylinder 1.4 oil outlet are sequentially connected through the hydraulic pipeline 5.2. The fast advance pump on-off valve 3.7 and the fast advance stop valve 3.3 are connected to the large-diameter hydraulic cylinder 1.1 oil outlet through the hydraulic pipeline 5.2, and a three-way pipe is arranged on the hydraulic pipeline 5.2. The slow advancing system 4 comprises a slow advance hydraulic pump 4.1 and a slow advance directional valve 4.2. The slow advance hydraulic pump 4.1 oil outlet and the slow advance directional valve 4.2 are connected through the hydraulic pipeline 5.2. The slow advance directional valve 4.2 outlet pipeline is respectively connected to the large-diameter hydraulic cylinder 1.1 oil inlet and oil outlet. The power source of the slow advance hydraulic pump 4.1 is a variable frequency motor. The auxiliary system 5 comprises a hydraulic oil tank 5.1. The hydraulic oil tank 5.1 is connected with the slow advance directional valve 4.2 oil return, the slow advance hydraulic pump 4.1 oil inlet, the fast advance hydraulic pump 3.6 oil inlet and the oil return valve 2.5 through the hydraulic pipeline 5.2.

[0076] In the embodiment, the slow advancing is used in the working condition of small displacement and high pressure. When the cutting tool with pressure cutting pipe column, the slow advancing is used to meet the requirements of flat cut and easy to lift the pipe column again. The slow advancing can realize slow and stable feeding speed and high thrust during cutting. When the variable-diameter piston of the variable-diameter hydraulic cylinder travels to the right end, the slow retraction is used to retract the piston of the variable-diameter hydraulic cylinder.

[0077] The slow advancing state and the slow retraction state of the hydraulic feeding device are controlled by the following steps:

[0078] 1) Turn on the power supply of the device;

[0079] 2) Slow forward valve 4.2 is adjusted to the cylinder pushing position;

[0080] 3) The inlet on-off valve 2.1 is opened;

[0081] 4) The fast forward pump on-off valve 3.7, the fast forward stop valve 3.3 and the return on-off valve 2.5 are closed respectively;

[0082] 5) After checking the valve position, the slow forward hydraulic pump 4.1 is opened to start the slow pushing work of the cylinder 2.3;

[0083] 6) The pushing speed in the slow pushing state is further adjusted by adjusting the frequency of the frequency conversion motor matched with the slow forward hydraulic pump 4.1;

[0084] 7) When the variable diameter piston 1.2 in the variable diameter cylinder 1 travels to the right end, the cylinder retraction is started;

[0085] 8) The power supply of the device is turned on, and the slow forward valve 4.2 is adjusted to the cylinder retraction position;

[0086] 9) The fast forward stop valve 3.3 is opened;

[0087] 10) The inlet on-off valve 2.1, the return on-off valve 2.5 and the fast forward pump on-off valve 3.7 are closed respectively;

[0088] 11) After checking the valve position, the slow forward hydraulic pump 4.1 is opened to start the slow retraction of the variable diameter piston 1.2, and the retraction is stopped until the variable diameter piston 1.2 is pushed to the left end.

[0089] Example 2

[0090] As shown in FIGS. Figure 1 , 3 and 4, the difference between the present example and example 1 is that the variable diameter cylinder 1 is further provided with a displacement scale 1.3, the displacement scale 1.3 is arranged at the end position near the variable diameter piston 1.2 of the large diameter cylinder 1.1, a one-way valve 2.2 is arranged on the pipeline between the inlet on-off valve 2.1 of the working system 2 and the working cylinder 2.3, a fast forward pressure gauge 3.4 and a fast forward overflow valve 3.5 are installed on the pipeline between the outlet of the fast forward hydraulic pump 3.6 of the fast pushing system 3 and the hydraulic oil tank 5.1, an inlet pressure sensor 3.1 and a safety overflow valve 3.2 are arranged on the pipeline between the fast forward stop valve 3.3 of the fast pushing system 3 and the outlet of the small diameter cylinder 1.4, and the rest of the structure is the same as that of example 1.

[0091] In this embodiment, the displacement scale 1.3 is used to monitor the position of the variable-diameter piston 1.2 in real time, preventing the situation of the piston top cylinder end; the one-way valve 2.2 prevents the oil inlet on-off valve 2.1 from being completely closed, and the hydraulic oil backflow causes the working cylinder 2.3 to be difficult to maintain the pressure; the fast forward overflow valve 3.5 can ensure that the pump outlet hydraulic pipeline 5.2 is safe and not overpressure when the fast forward hydraulic pump 3.6 is mistakenly opened without opening the fast forward pump on-off valve 3.7; by adjusting the overflow value of the safety overflow valve 3.2, the working system 2 and the hydraulic pipeline 5.2 can be ensured to be safe and not overpressure.

[0092] In this embodiment, the fast forward is used in the working condition that the working cylinder needs to advance at a faster speed, such as cutting the pipe column with the cutting tool under pressure as described above. Before the cutting tool contacts the pipe column to be cut, fast forward can be performed to save time. When the variable-diameter piston of the variable-diameter cylinder travels to the right end, the piston can be retracted by fast backward cylinder. Fast backward cylinder can save operation time and improve efficiency.

[0093] The fast forward state and the fast backward state of the hydraulic feeding device are controlled by the following steps:

[0094] 1) Turn on the power supply of the device;

[0095] 2) Adjust the slow forward directional valve 4.2 to the middle position;

[0096] 3) Open the fast forward pump on-off valve 3.7, the fast forward stop valve 3.3, and the oil inlet on-off valve 2.1, respectively;

[0097] 4) Close the oil return on-off valve 2.5;

[0098] 5) After checking that the valve positions are correct, open the fast forward hydraulic pump 3.6 to start the fast forward working cylinder 2.3;

[0099] 6) When the variable-diameter piston 1.2 in the variable-diameter cylinder 1 travels to the right end, its stroke has been completed, and it needs to be retracted to the left end for further advancement;

[0100] 7) Turn on the power supply of the device and adjust the slow forward directional valve 4.2 to the middle position;

[0101] 8) Open the fast forward pump on-off valve 3.7 and the fast forward stop valve 3.3, respectively;

[0102] 9) Close the oil inlet on-off valve 2.1 and the oil return on-off valve 2.5, respectively;

[0103] 10) After checking that the valve positions are correct, open the fast forward hydraulic pump 3.6 to start the fast backward variable-diameter piston 1.2 until it stops after being pushed to the left end.

[0104] Embodiment 3

[0105] AsFigure 1 、 2 And 4, the difference between this embodiment and embodiment 1 is that the slow-advance hydraulic pump 4.1 is equipped with a slow-advance pressure gauge 4.4 and a slow-advance overflow valve 4.3, and the rest of the structure is the same as that of embodiment 1.

[0106] In this embodiment, the slow-advance overflow valve 4.3 can ensure that the pump outlet hydraulic pipeline 5.2 is safe and not over-pressured when the fast-advance hydraulic pump 3.6 is mistakenly opened without opening the fast-advance pump on-off valve 3.7.

[0107] In this embodiment, slow advance is used in the working condition requiring small displacement and high pressure, such as cutting the pipe column with the cutting tool under pressure, which needs to meet the requirements of smooth cutting and easy lifting of the pipe column. Slow advance can achieve slow and stable feed speed and high thrust during cutting. When the variable-diameter piston in the variable-diameter hydraulic cylinder travels to the right end, the piston in the variable-diameter hydraulic cylinder can be retracted by fast retracting the cylinder, which can save working time and improve efficiency.

[0108] The slow advance state and the fast retracting state of the hydraulic feeding device are controlled by the following steps:

[0109] 1) Turn on the power supply of the device;

[0110] 2) Adjust the slow-advance directional valve 4.2 to the push cylinder position;

[0111] 3) Open the oil inlet on-off valve 2.1;

[0112] 4) Close the fast-advance pump on-off valve 3.7, the fast-advance stop valve 3.3, and the oil return on-off valve 2.5, respectively;

[0113] 5) After checking that the valve positions are correct, open the slow-advance hydraulic pump 4.1 to start slow advance of the working cylinder 2.3;

[0114] 6) The advance speed in the slow advance state can be further adjusted by adjusting the frequency of the frequency conversion motor matched with the slow-advance hydraulic pump 4.1;

[0115] 7) When the variable-diameter piston 1.2 in the variable-diameter hydraulic cylinder 1 travels to the right end, its stroke has been completed, and it needs to be retracted to the left end for further advance;

[0116] 8) Turn on the power supply of the device and adjust the slow-advance directional valve 4.2 to the neutral position;

[0117] 9) Open the fast-advance pump on-off valve 3.7 and the fast-advance stop valve 3.3, respectively;

[0118] 10) Close the oil inlet on-off valve 2.1 and the oil return on-off valve 2.5, respectively;

[0119] 11) Check the valve position is correct, open the fast forward hydraulic pump 3.6 start fast back to the variable diameter piston 1.2, until it is pushed to the left end after stopping.

[0120] Example 4

[0121] As shown in Figure 1 and 6 , the difference between this embodiment and example 1 is that the fast forward stop valve 3.3 of the fast forward system 3 and the oil outlet of the small diameter cylinder 1.4 are provided with an oil inlet pressure sensor 3.1 and a safety overflow valve 3.2, the oil return on-off valve 2.5 of the working system 2 and the hydraulic oil tank 5.1 are provided with a visual exhaust device 2.7, the oil return pressure sensor 2.4 is arranged between the oil outlet of the rodless cavity of the working cylinder 2.3 and the oil return on-off valve 2.5, and the oil return speed regulating valve 2.6 is arranged between the oil return on-off valve 2.5 and the hydraulic oil tank 5.1, and the rest of the structure is the same as example 1.

[0122] In this embodiment, by adjusting the overflow value of the safety overflow valve 3.2, the safety of the working system 2 and the hydraulic pipeline 5.2 can be guaranteed without overpressure; the visual exhaust device 2.7 can observe the situation of bubbles coming out of the oil return through its glass window to determine whether there is air entering and discharge the gas in the working cylinder 2.3, and the oil return speed can be controlled by operating the oil return speed regulating valve 2.6 to prevent the high-pressure gas-containing oil from being quickly discharged from the exhaust port of the visual exhaust device 2.7.

[0123] In this embodiment, when the working cylinder is used for the first time, long-term non-use or other oil return through the visual exhaust device, the situation of bubbles in the oil return should be observed through the window of the exhaust device to determine whether the system should be circulated and exhausted.

[0124] The circulating exhaust state of the hydraulic feeding device is controlled by the following steps:

[0125] 1) When the working cylinder 2.3 is used for the first time, long-term non-use or other judgment of the situation of bubbles in the internal, it should be circulated and exhausted;

[0126] 2) Turn on the power of the device, and adjust the slow forward reversing valve 4.2 to the middle position;

[0127] 3) Turn on the fast forward pump on-off valve 3.7, the fast forward stop valve 3.3, the oil inlet on-off valve 2.1 and the oil return on-off valve 2.5 respectively;

[0128] 4) Check the valve position is correct, open the fast forward hydraulic pump 3.6 start circulating exhaust;

[0129] 5) During the circulation, pay attention to the oil return state displayed on the glass window of the visual exhaust device 2.7;

[0130] 6) Stop the exhaust after no bubbles are observed in the visual exhaust device 2.7 glass window.

[0131] 7) After 30 minutes, repeat the cycle of pressurizing and venting as described above until no bubbles are observed in the oil return.

[0132] It is to be understood that the present application is described by way of example only, and that modifications and alterations can be made to the features and embodiments described herein without departing from the spirit and scope of the application. In addition, modifications and alterations can be made to the features and embodiments described herein to adapt them to specific situations and materials without departing from the spirit and scope of the application. Accordingly, the application is not limited to the specific embodiments disclosed herein, but rather, all embodiments falling within the scope of the claims are intended to be embraced by the application.

Claims

1. A hydraulic feed device, characterized by: Comprising, Variable diameter hydraulic cylinder (1), the variable diameter hydraulic cylinder (1) includes large diameter hydraulic cylinder (1.1), variable diameter piston (1.2) and small diameter hydraulic cylinder (1.4), the large diameter hydraulic cylinder (1.1) and small diameter hydraulic cylinder (1.4) are coaxially arranged, the variable diameter piston (1.2) includes intermediate piston rod and two ends respectively with large diameter hydraulic cylinder (1.1) and small diameter hydraulic cylinder (1.4) matched piston head, the piston head is arranged in large diameter hydraulic cylinder (1.1) and small diameter hydraulic cylinder (1.4) respectively, the variable diameter piston (1.2) is pushed by supplying liquid to large diameter hydraulic cylinder (1.1), and the variable diameter piston (1.2) pushes small diameter hydraulic cylinder (1.4) again; Work system (2), the work system (2) includes oil inlet on-off valve (2.1), one-way valve (2.2) work liquid cylinder (2.3), oil return on-off valve (2.5) and oil return speed regulating valve (2.6), the oil inlet on-off valve (2.1) is connected with the oil outlet of small diameter hydraulic cylinder (1.4) through hydraulic pipeline (5.2) one end, the other end of oil inlet on-off valve (2.1) is connected with the oil inlet of one-way valve (2.2), the oil outlet of one-way valve (2.2) is connected with the oil inlet of work liquid cylinder (2.3) without rod cavity, the oil outlet of work liquid cylinder (2.3) without rod cavity is connected with oil return on-off valve (2.5), oil return speed regulating valve (2.6) and hydraulic oil tank (5.1) in turn; Fast advance system (3), the fast advance system (3) includes fast advance cut-off valve (3.3), fast advance hydraulic pump (3.6) and fast advance pump on-off valve (3.7), the oil outlet of fast advance hydraulic pump (3.6), fast advance pump on-off valve (3.7), fast advance cut-off valve (3.3) and small diameter hydraulic cylinder (1.4) oil outlet are connected in turn through hydraulic pipeline (5.2), the fast advance pump on-off valve (3.7) and fast advance cut-off valve (3.3) are connected to the oil outlet of large diameter hydraulic cylinder (1.1) through hydraulic pipeline (5.2) on the hydraulic pipeline (5.2) between them are equipped with three ways, and are connected to the oil outlet of large diameter hydraulic cylinder (1.1) through hydraulic pipeline (5.2); Slow advance system (4), the slow advance system (4) includes slow advance hydraulic pump (4.1) and slow advance reversing valve (4.2), the oil outlet of slow advance hydraulic pump (4.1) and slow advance reversing valve (4.2) are connected through hydraulic pipeline (5.2), the outlet pipeline of slow advance reversing valve (4.2) is connected to the oil inlet and oil outlet of large diameter hydraulic cylinder (1.1) respectively, and the power source of slow advance hydraulic pump (4.1) is variable frequency motor; Auxiliary system (5), the auxiliary system (5) includes hydraulic oil tank (5.1), the hydraulic oil tank (5.1) is connected with the oil return port of slow advance reversing valve (4.2), the oil inlet of slow advance hydraulic pump (4.1) and the oil inlet of fast advance hydraulic pump (3.6) through hydraulic pipeline (5.2) respectively. The variable diameter hydraulic cylinder (1) is further provided with displacement scale (1.3) for monitoring the position of variable diameter piston (1.2) in real time, and the displacement scale (1.3) is arranged at the end position of the large diameter hydraulic cylinder (1.1) near the variable diameter piston (1.2).

2. The hydraulic feed apparatus according to claim 1, characterized by: The oil return on-off valve (2.5) and the hydraulic oil tank (5.1) of the work system (2) are provided with visible exhaust device (2.7).

3. The hydraulic feed apparatus according to claim 1, characterized by: ​ 4. The hydraulic feed apparatus according to claim 1, characterized by: The pipeline between the rodless cavity oil outlet of the working system (2) and the oil return on-off valve (2.5) is provided with an oil return pressure sensor (2.4).

5. The hydraulic feed apparatus according to claim 1, wherein: The pipeline between the oil outlet of the fast advance hydraulic pump (3.6) of the fast advance system (3) and the hydraulic oil tank (5.1) is provided with a fast advance pressure gauge (3.4) and a fast advance overflow valve (3.5).

6. The hydraulic feed apparatus according to claim 1, wherein: The pipeline between the fast advance stop valve (3.3) of the fast advance system (3) and the oil outlet of the small-diameter hydraulic cylinder (1.4) is provided with an oil inlet pressure sensor (3.1) and a safety overflow valve (3.2).

7. The hydraulic feed apparatus according to claim 1, wherein: The oil outlet of the slow advance hydraulic pump (4.1) is provided with a slow advance pressure gauge (4.4) and a slow advance overflow valve (4.3).

8. A control method of the hydraulic feeding device according to any one of claims 1-7, comprising the following four working states: a slow advance state, a fast advance state, a fast return of the variable-diameter piston (1.2) state and a slow return of the variable-diameter piston (1.2) state. The control steps of the slow advance state are as follows: 1) Turn on the power supply of the device; 2) Adjust the slow advance directional valve (4.2) to the cylinder advancing position; 3) Open the oil inlet on-off valve (2.1); 4) Close the fast advance pump on-off valve (3.7), the fast advance stop valve (3.3) and the oil return on-off valve (2.5) respectively; 5) After checking the correct valve position, open the slow advance hydraulic pump (4.1) to start the slow advance of the working hydraulic cylinder (2.3); 6) Further adjust the advance speed in the slow advance state by adjusting the frequency of the frequency conversion motor matched with the slow advance hydraulic pump (4.1); The control steps of the fast advance state are as follows: 1) Turn on the power supply of the device; 2) Adjust the slow advance directional valve (4.2) to the middle position; 3) Open the fast advance pump on-off valve (3.7), the fast advance stop valve (3.3) and the oil inlet on-off valve (2.1) respectively; 4) Close the oil return on-off valve (2.5); 5) After checking the correct valve position, open the fast advance hydraulic pump (3.6) to start the fast advance of the working hydraulic cylinder (2.3); The control steps of the fast return of the variable-diameter piston (1.2) state are as follows: 1) When the variable-diameter piston (1.2) in the variable-diameter hydraulic cylinder (1) travels to the right end, its stroke has been completed, and it needs to be returned to the left end to advance again; 2) Turn on the power supply of the device and adjust the slow advance directional valve (4.2) to the middle position; 3) Open the fast advance pump on-off valve (3.7) and the fast advance stop valve (3.3) respectively; 4) Close the oil inlet on-off valve (2.1) and the oil return on-off valve (2.5) respectively; 5) After checking the correct valve position, open the fast advance hydraulic pump (3.6) to start the fast return of the variable-diameter piston (1.2) until it is pushed to the left end and then stops; The control steps of the slow return of the variable-diameter piston (1.2) state are as follows: 1) When the variable-diameter piston (1.2) in the variable-diameter hydraulic cylinder (1) travels to the right end, it starts to return; 2) Turn on the power supply of the device and adjust the slow advance directional valve (4.2) to the cylinder retreating position; 3) Open the fast advance stop valve (3.3); 4) Close the oil inlet on-off valve (2.1), the oil return on-off valve (2.5) and the fast advance pump on-off valve (3.7) respectively; 5) After checking the valve position is correct, open the slow hydraulic pump (4.1) to start slow back to variable diameter piston (1.2), until it is pushed to the left end after stopping.

9. The control method according to claim 8, characterized in that: The control method further comprises a circulating exhaust state, The control method further comprises a circulating exhaust state, 1) When the working cylinder (2.3) is first used, long-term unused or other conditions that the inside of the working cylinder (2.3) has bubbles, the working cylinder (2.3) should be circulated and exhausted; 2) Turn on the power of the device, and adjust the slow forward reversing valve (4.2) to the middle position; 3) Turn on the fast forward pump on-off valve (3.7), the fast forward stop valve (3.3), the oil inlet on-off valve (2.1), and the oil return on-off valve (2.5) respectively; 4) After checking the valve position is correct, open the fast hydraulic pump (3.6) to start circulating and exhausting; 5) During the circulation, pay attention to the oil return state displayed on the glass window of the visual exhaust device (2.7); 6) Stop the exhaust after observing that there is no bubble on the glass window of the visual exhaust device (2.7); 7) After standing for 30 minutes, circulate and exhaust again according to the above steps until no bubbles come out in the oil return.

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