阅读说明：本技术 一种核燃料棒端塞压力电阻焊加压装置及焊接方法 (Pressure resistance welding pressurizing device and welding method for nuclear fuel rod end plug ) 是由 李铜 张鹏程 徐磊 李玉斌 何建军 魏汉兵 段家宝 夏胜全 潘际宇 种可可 于 2019-12-26 设计创作，主要内容包括：本发明提供一种核燃料棒端塞压力电阻焊加压装置及焊接方法,装置包括顶锻电缸、压力传感器、浮动接头、导向调整机构、位移传感器、端塞座、电极杆、包壳管、焊接室、气动执行机构；顶锻电缸安装在基座上,顶锻电缸的一端与伺服电机相连,由伺服电机提供执行动力,另一端连接浮动接头,浮动接头正对电极杆,电极杆安装在导向调整机构上,电极杆与浮动接头接触一端安装有压力传感器,压力传感器用于和控制器相连,端塞座安装在中空的电极杆的另一端部,并且电极杆内提供负压,用于吸附住端塞座。本发明提供一种核燃料棒端塞压力电阻焊加压装置,在端塞压力电阻焊通电及加压为毫秒级的焊接方式中,能够实现精确快速压力,精确快速位置控制。(The invention provides a pressure resistance welding pressurizing device and a welding method for a nuclear fuel rod end plug, wherein the device comprises an upsetting electric cylinder, a pressure sensor, a floating joint, a guide adjusting mechanism, a displacement sensor, an end plug seat, an electrode rod, a cladding tube, a welding chamber and a pneumatic actuating mechanism; the upset electric cylinder is installed on the base, and the one end of upset electric cylinder links to each other with servo motor, is provided execution power by servo motor, and floating joint is connected to the other end, and floating joint is just to the electrode stem, and the electrode stem is installed on direction guiding mechanism, and pressure sensor is installed with floating joint contact one end to the electrode stem, and pressure sensor is used for linking to each other with the controller, and end plug seat installs another tip at hollow electrode stem to provide the negative pressure in the electrode stem, be used for adsorbing the end plug seat. The invention provides a pressure resistance welding pressurizing device for a nuclear fuel rod end plug, which can realize accurate and rapid pressure and accurate and rapid position control in a welding mode that the pressure resistance welding of the end plug is electrified and pressurized to millisecond level.)

1. A pressure resistance welding pressurizing device for a nuclear fuel rod end plug is characterized by comprising an upsetting electric cylinder, a pressure sensor, a floating joint, a guide adjusting mechanism, a displacement sensor, an end plug seat, an electrode rod, a cladding tube, a welding chamber and a pneumatic actuating mechanism;

the upsetting electric cylinder is arranged on the base, one end of the upsetting electric cylinder is connected with the servo motor, the servo motor provides execution power, the other end of the upsetting electric cylinder is connected with the floating joint, the floating joint is opposite to the electrode rod, the electrode rod is arranged on the guide adjusting mechanism, one end of the guide mechanism is arranged on the base, the other end of the guide mechanism is arranged on the welding chamber, one end of the electrode rod, which is in contact with the floating joint, is provided with the pressure sensor, the pressure sensor is used for being connected with the controller, the end plug seat is arranged at the other end of the hollow electrode rod, negative pressure is provided in the electrode rod and is used for adsorbing the end plug seat, one side of the end plug seat is provided with the;

the cladding tube is fixed on the pneumatic actuator at the other side, the clamping part is arranged at the top of the pneumatic actuator and used for clamping and fixing the cladding tube and ensuring that the end parts are flush, and the pneumatic actuator provides power for the cladding tube to move towards the welding chamber.

2. A nuclear fuel rod end plug pressure resistance welding pressurizing device as recited in claim 1, wherein the guide adjusting mechanism comprises linear guide rails and slide rails, the 2 linear guide rails are arranged in a diagonal balance mode, one end of each linear guide rail is installed on the base, the other end of each linear guide rail is installed on the welding chamber, the cross section of each slide rail is circular, and the slide rails are sleeved on the linear guide rails arranged in parallel in the diagonal direction.

3. A nuclear fuel rod end plug pressure resistance welding pressurizing device as recited in claim 1, wherein the welding chamber comprises a welding chamber, a welding electrode, a sealing ring and a cladding tube clamp, the cladding tube clamp is sequentially arranged in the welding chamber from left to right, the welding electrode is used for electrifying the cladding tube to realize accurate welding, the sealing ring is an inflatable rubber ring for realizing air isolation on one side of the cladding tube, and the cladding tube clamp is used for fixing the cladding tube in the welding chamber.

4. A nuclear fuel rod end plug pressure resistance welding pressurization device according to claim 1, characterized in that the cladding tube clamp is a milling machine pneumatic chuck of a CNC system.

5. A pressure resistance welding pressurizing device for a nuclear fuel rod end plug according to claim 1, wherein a suction hole for sucking air and a gas filling hole for filling a protective atmosphere are further provided on a top surface of the welding chamber.

6. The nuclear fuel rod end plug pressure resistance welding pressurizing device as recited in claim 1, wherein the controller is connected with a welding power supply and a servo motor, and the welding power supply has two control modes of constant current and constant power.

7. A pressure resistance welding pressurizing device for a nuclear fuel rod end plug according to claim 1, wherein an inlet on one side of the welding chamber end plug seat is provided with an air-filled sealing ring for wrapping the electrode rod during welding and blocking air of the end plug seat.

8. A nuclear fuel rod end plug pressure resistance welding pressurizing device according to claim 1, wherein a sensor for measuring displacement is mounted on the leftmost clamping portion of the pneumatic actuator, and the displacement sensor is connected to a controller for controlling the position of the cladding tube moving toward the welding chamber.

9. A welding method of a pressure resistance welding pressurizing device of a nuclear fuel rod end plug is characterized by comprising the following steps:

step 1, mounting an end plug seat at one end of an electrode rod, adsorbing the end plug seat by the electrode rod through negative pressure, mounting a cladding tube on a clamping part of a pneumatic actuator, and keeping the end part of the cladding tube parallel and level;

step 2, the pneumatic actuating mechanism moves towards the welding chamber, the displacement sensor is used for measuring the movement displacement of the cladding tube, and when the pneumatic actuating mechanism moves to the welding position, the cladding tube clamp is used for clamping the cladding tube;

step 3, the controller controls the servo motor to enable the upsetting electric cylinder to move towards one side of the welding chamber, and the end plug seat enters a preset position in the welding chamber;

step 4, inflating the sealing ring on one side of the cladding tube and the sealing ring on one side of the electrode rod, after a period of time, pumping out air in the welding chamber by using an air pumping hole at the top of the welding chamber, and after a period of time, filling protective atmosphere with certain air pressure into the welding chamber;

and 5, controlling a welding power supply to electrify the electrode rod and the welding electrode by the controller, controlling the servo motor to continuously provide power for upsetting to the right side, and mastering the welding quality and adjusting the welding mode in real time through the pressure sensor and the displacement sensor in the execution process.

10. The method for welding a pressurizing device for pressure resistance welding of a nuclear fuel rod end plug according to claim 9, wherein in the step 4, the protective atmosphere is low-pressure helium, and the welding power supply has two control modes of constant current and constant power.

Technical Field

The invention belongs to the technical field of nuclear energy utilization equipment, and particularly relates to a resistance welding pressurizing device and a welding method.

Background

The zirconium tube structure is shown in figure 1, the function of the zirconium tube structure is to store nuclear fuel and realize the isolation of the nuclear fuel from the medium outside the rod, and the main structure is that the middle tube and the end plug are formed by welding. The most popular joining method at present is pressure resistance welding used by USW and russia VVER in france, besides the original traditional fusion welding, and the welding principle of the two is similar to that shown in fig. 2, wherein 101-end plug electrode, 102-pneumatic actuator, 103-extended cladding tube, 104-welding chamber, 105-welding electrode, 106-sealing ring and 107-cladding tube clamp (collet).

The pressure resistance welding process comprises the following steps: the end plug is positioned with the tube and pre-stress is applied (forming a local contact surface) -the welding current is switched on and welding pressure is applied (heating and plastic forming near the contact surface completes the weld joint).

The welded joint requires a smooth outer surface without machining; the formation of extrusion flash on the inner surface indicates that the weld has sufficient plastic deformation to achieve reliable joining.

The formation of the welding seam requires pressure and current (provides heat to form a temperature field suitable for joint forming), and under the condition of certain machining size and shape and pre-pressure of the contact surface, the contact form of the contact surface determines that the contact resistance is an important factor directly influencing the welding temperature field. The current end plug pressure resistance welding adopts a gas power source and has the following defects:

(1) the response is slow, and the accurate matching between the loading pressure, speed, displacement and current cannot be achieved.

(2) The output force is unstable and the maintenance work is increased due to piston air leakage, lubrication and maintenance between the piston and the cylinder body and the like.

However, in the prior art, the pneumatic actuator is replaced by the electric actuator, and the components of the original pneumatic actuator cannot respond in time, so that the welding effect of the fuel rod end plug cannot be achieved, and the existing welding mode is still in the pneumatic actuator mode.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a pressure resistance welding pressurizing device and a welding method for a nuclear fuel rod end plug.

The invention adopts the following technical scheme:

a pressure resistance welding pressurizing device for a nuclear fuel rod end plug comprises an upsetting electric cylinder, a pressure sensor, a floating joint, a guide adjusting mechanism, a displacement sensor, an end plug seat, an electrode rod, a cladding tube, a welding chamber and a pneumatic actuating mechanism.

The upsetting electric cylinder is arranged on the base, one end of the upsetting electric cylinder is connected with the servo motor, the servo motor provides execution power, the other end of the upsetting electric cylinder is connected with the floating joint, the floating joint is opposite to the electrode rod, the electrode rod is arranged on the guide adjusting mechanism, one end of the electrode rod, which is in contact with the floating joint, is provided with the pressure sensor, the pressure sensor is used for being connected with the controller, the end plug seat is arranged at the other end of the hollow electrode rod, negative pressure is provided in the electrode rod and is used for adsorbing the end plug seat, one side of the end plug seat is provided with the displacement sensor used for measuring the displacement of the end plug seat;

the direction guiding mechanism comprises linear guide rails and slide rails, wherein 2 linear guide rails are arranged in a diagonal balance mode, one end of each linear guide rail is installed on the base, the other end of each linear guide rail is installed on the welding chamber, the cross section of each slide rail is circular, and the slide rails are sleeved on the linear guide rails arranged in parallel on the diagonals.

The cladding tube is fixed on the pneumatic actuator at the other side, three clamping parts are arranged at the top of the pneumatic actuator and used for clamping and fixing the cladding tube and ensuring that the end parts are flush, and the pneumatic actuator provides power for the cladding tube to move towards the welding chamber.

The pneumatic actuating mechanism comprises 3 clamping parts, namely a front end clamping part, a middle clamping part and a rear end clamping part, wherein the front end clamping part is movably arranged on a front end clamping part mounting seat, the middle clamping part is arranged on a movable slide rail, the rear end clamping part is arranged on a polished rod guide rail, and the front end clamping part mounting seat, the movable slide rail and the polished rod guide rail are respectively arranged on respective bases.

The welding chamber comprises a welding chamber, a welding electrode, a sealing ring, a cladding tube clamp, the welding chamber, the welding electrode and the sealing ring, the cladding tube clamp is sequentially arranged in the welding chamber from left to right, the welding chamber is used for welding an end plug seat and the cladding tube, the welding electrode is used for electrifying the cladding tube and corresponds to an electrode rod to realize accurate welding, the sealing ring is an inflatable rubber ring and is used for realizing air isolation of one side of the cladding tube, and the cladding tube clamp is used for fixing the cladding tube in the welding chamber.

Cladding tube clamps or milling machine pneumatic chucks for CNC systems.

The top surface of the welding chamber 9 is also provided with an air exhaust hole for exhausting air and an air supplement hole for supplementing protective atmosphere.

The controller is connected with the welding power supply and the servo motor. The welding power supply has two control modes of constant current and constant power.

The further technical scheme is that an air inflation sealing ring is arranged at an inlet at one side of the end plug seat 6 of the welding chamber 40 and used for wrapping the electrode rod 7 during welding and isolating the air of the end plug seat 6.

The further technical scheme is that a sensor for measuring displacement is mounted on the leftmost clamping part of the pneumatic actuating mechanism, and the displacement sensor is connected with the controller and used for controlling the position of the cladding tube moving to the welding chamber.

In addition, the welding method of the invention comprises the following steps:

step 1, installing an end plug seat at one end of an electrode rod, adsorbing the end plug seat by the electrode rod through negative pressure, installing a cladding tube on a clamping part of a pneumatic actuator, and keeping the end part of the cladding tube flush.

And 2, moving the pneumatic actuating mechanism to the welding chamber, measuring the moving displacement of the cladding tube by using the displacement sensor, and clamping the cladding tube by using a cladding tube clamp when the cladding tube moves to the welding position.

And 3, controlling the servo motor by the controller to enable the upsetting electric cylinder to move towards one side of the welding chamber, and enabling the end plug seat to enter a preset position in the welding chamber.

And 4, inflating the sealing ring on one side of the cladding tube and the sealing ring on one side of the electrode rod, pumping out air in the welding chamber by using the air pumping hole at the top of the welding chamber after a period of time, and filling protective atmosphere with certain air pressure into the welding chamber after a period of time.

And 5, controlling a welding power supply to electrify the electrode rod and the welding electrode by the controller, controlling the servo motor to continuously provide power for upsetting to the right side, and mastering the welding quality and adjusting the welding mode in real time through the pressure sensor and the displacement sensor in the execution process.

Further, the protective atmosphere is low-pressure helium.

In a further aspect, the welding power supply has two control modes, a constant current control mode and a constant power control mode.

The invention has the beneficial effects that:

1. the upsetting electric cylinder adopts the servo motor as a power source, the pressure in the welding process is controlled, the response speed is high, the pressure control precision is high, and the process experiment and the product development of multiple materials and multiple specifications can be realized by combining the welding current combination process.

And the traditional USW welding equipment adopts a cylinder as an upsetting mechanism, the cylinder is simple to realize and low in cost, but the pressure in the welding process cannot be changed quickly (the pressure change response speed is not high enough). It is very difficult to achieve a multi-step pressure curve.

2. The end plug electrode rod guide adopts a symmetrical structure linear guide rail guide; and USW welding equipment adopts the frame structure, utilizes bottom surface linear guide as the direction, and linear guide installs one side, and the welding upset sometimes atress is inhomogeneous problem.

3. During welding, the clamping of the cladding tube is not performed by vacuum adsorption, meanwhile, the welding is not performed in high-pressure atmosphere, the clamping of the end plug is realized by adopting a pneumatic collet chuck (cladding tube clamp), and a protective atmosphere is formed around a welding chamber area by filling low-pressure helium gas during welding, so that the purpose of protecting a welding seam is achieved.

On the other hand, the negative pressure adsorption end plug seat is continuously used, an inflatable sealing ring (rubber ring) can be used for blocking the structure of the electrode rod, the electrode rod is sealed, the pressure sensor and the displacement sensor are designed to position the end plug seat, the welded fuel rod end plug cannot deform, and the USW directly adopts two-stage sealing rings for processing the electrode rod.

And 4, the VVER fuel rod (cladding tube) is clamped by using collet jaws, but the electrode (welding electrode) is in a 3-jaw mode, and meanwhile, different welding power supplies have very high requirements on electrode material matching and are not suitable for use.

At present, in the prior art, an AFA3G electrode block structure is adopted, in the specific structure of the AFA3G fuel rod clamping mechanism, an electrode block (welding electrode) is formed by 2-segment arc surfaces, a power supply adopts medium-frequency inversion, and the technical maturity is high.

Both the VVER fuel rod and AFA3G fuel rod have the problem that the electrode block is a clamping block,

the pneumatic collet mechanism is a standard product on the market, is similar to a CNC (computerized numerical control) machine head milling cutter chuck, has multiple jaws, large friction force, large effective contact surface and large molded surface number, is not easy to damage the cladding tube, and realizes a mode of separately designing a welding electrode and a cladding tube clamp.

5. The cladding tube is realized by adopting the inflatable sealing ring, when the cladding tube is fed in, the inflatable sealing ring does not feed gas, the inner ring of the sealing ring retracts under the elastic action of materials, the diameter of the inner ring is increased, and the cladding tube can smoothly enter; when the cladding tube is in place, the sealing ring is inflated with gas, and the inner ring of the sealing ring is expanded to form a better sealing surface with the cladding tube.

6. The invention utilizes the controller to preset variable adjustment of current and pressure curves in the welding process, so that the equipment has more excellent process performance;

the welding method and the principle of the invention will create new technical bright points from the structural aspect and the product service performance aspect:

the configured welding power supply has two control modes of constant current and constant power;

the configured welding system has a high-response-speed pressure control technology for accurately adjusting pre-welding prepressing, constant pressure in the welding process and pressure maintaining after welding;

the high response pressure control speed and the welding high response current control form a combination to adapt to the process requirements of different materials and specifications.

The device of the invention changes pneumatic execution into electric execution, solves the problem that the original accessory part can not respond to the electric execution welding mode in time, and the invention finds out the condition of the welding mode which needs to respond to the electric execution quickly through comprehensive analysis, wherein the sealing performance during welding, the current magnitude during welding, the welding pressure magnitude and the displacement magnitude are required to be ensured, and all factors have relevance and are a combination factor, therefore, in order to ensure the sealing performance during welding, the current magnitude during welding, the welding pressure magnitude and the displacement magnitude, the clamping and sealing of the cladding tube, the clamping and sealing of the end plug seat are realized, and the control of the welding pressure and the displacement are all relevant.

Drawings

FIG. 1 is a schematic structural view of a zirconium tube;

FIG. 2 is a schematic structural diagram of a typical foreign pressure resistance welding device;

FIG. 3 is a schematic view of a pressure welding process of the improved electric actuator;

FIG. 4 is a block diagram of the present invention (excluding pneumatic actuators);

FIG. 5 is a block diagram of the pneumatic actuator of the present invention;

FIG. 6 is a front view of the pneumatic actuator;

FIG. 7 is a top view of the pneumatic actuator;

fig. 8 is a side view of a pneumatic actuator.

In the figure: 1-upsetting electric cylinder, 2-pressure touch sensor, 3-floating joint, 4-guiding adjusting mechanism, 5-displacement sensor, 6-end plug seat, 7-electrode rod, 8-cladding tube, 9-welding chamber and 10-pneumatic actuating mechanism;

40-welding chamber, 50-welding electrode, 6-sealing ring and 70-cladding tube clamp;

101-a front end clamping part, 102-a middle clamping part and 103-a rear end clamping part;

104-front end clamping part mounting base, 105-movable sliding rail and 106-polished rod guide rail.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described below clearly and completely, and it is obvious that the described embodiments are some, not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 3 and 4, a pressure resistance welding pressurizing device for a nuclear fuel rod end plug of the invention,

the device comprises an upsetting electric cylinder 1, a pressure sensor 2, a floating joint 3, a guide adjusting mechanism 4, a displacement sensor 5, an end plug seat 6, an electrode rod 7, a cladding tube 8, a welding chamber 9 and a pneumatic actuating mechanism 10.

The upset electric cylinder 1 is installed on the base, the one end of upset electric cylinder 1 links to each other with servo motor, provide execution power by servo motor, floating joint 3 is connected to the other end, floating joint 3 is just to electrode stem 7, electrode stem 7 is installed on direction guiding mechanism 4, electrode stem 7 is installed pressure sensor 2 with floating joint 3 contact one end, pressure sensor 2 is used for linking to each other with the controller, a pressure size for perception upset, end plug seat 6 is installed at another tip of hollow electrode stem 7, and provide the negative pressure in the electrode stem 7, be used for adsorbing end plug seat 6, displacement sensor 6 that is used for measuring end plug seat 6 displacement is installed to end plug seat 6 one side, displacement sensor 6 is used for linking to each other with the controller.

The guide adjusting mechanism 4 comprises linear guide rails and slide rails, wherein 2 linear guide rails are arranged in a diagonal balance mode, one ends of the linear guide rails are installed on the base, the other ends of the linear guide rails are installed on the welding chamber 9, the cross sections of the slide rails are circular, and the slide rails are sleeved on the linear guide rails arranged in parallel in the diagonal direction.

The cladding tube 8 is fixed on a pneumatic actuator 10 on the other side, three clamping parts are arranged at the top of the pneumatic actuator 10 and used for clamping and fixing the cladding tube 8 and ensuring that the end parts are flush, and the pneumatic actuator provides power for moving the cladding tube 8 to the welding chamber 9.

As shown in fig. 5-8, the pneumatic actuator includes 3 clamping portions, which are a front clamping portion 101, a middle clamping portion 102, and a rear clamping portion 103, wherein the front clamping portion 101 is movably mounted on a front clamping portion mounting seat 104, the middle clamping portion 102 is mounted on a movable slide rail 105, the rear clamping portion 103 is mounted on a polish rod guide rail 106, and the front clamping portion mounting seat 104, the movable slide rail 105, and the polish rod guide rail 106 are mounted on their respective bases.

The welding chamber 9 comprises a welding chamber 40, a welding electrode 50, a sealing ring 60 and a cladding tube clamp 70, the welding chamber 40, the welding electrode 50 and the sealing ring 60 are sequentially arranged in the welding chamber from left to right, the welding chamber 40 is used for welding the end plug seat 6 and the cladding tube 8, the welding electrode 50 is used for electrifying the cladding tube 8 and corresponds to the electrode rod 7 to realize accurate welding, the sealing ring 60 is an inflatable rubber ring and is used for realizing air isolation of one side of the cladding tube 8, and the cladding tube clamp 70 is used for fixing the cladding tube 8 in the welding chamber 9.

6 high accuracy displacement sensor divide 3 directions and install on welding chamber 9, and before cladding pipe 8 got into, displacement sensor was in the state of withdrawing, gave way out cladding pipe 8 access channel, and displacement sensor sensing head contacted with cladding pipe 8 after cladding pipe 8 got into can judge position data simultaneously and regard as the displacement data of cladding pipe 8 in welding chamber 9, regard as reference basis and the judged result of adjusting end chock 6 with this after end chock 6 side got into.

Cladding tube fixture 70 is either a milling machine pneumatic chuck of a CNC system.

The top surface of the welding chamber 9 is also provided with an air exhaust hole for exhausting air and an air supplement hole for supplementing protective atmosphere.

The controller is connected with the welding power supply and the servo motor. The welding power supply has two control modes of constant current and constant power.

The further technical scheme is that an air inflation sealing ring is arranged at an inlet at one side of the end plug seat 6 of the welding chamber 40 and used for wrapping the electrode rod 7 during welding and isolating the air of the end plug seat 6.

The further technical scheme is that a sensor for measuring displacement is mounted on the leftmost clamping part of the pneumatic actuating mechanism, and the displacement sensor is connected with the controller and used for controlling the position of the cladding tube moving to the welding chamber.

The operation method of the invention is as follows:

step 1, installing an end plug seat 6 at one end of an electrode rod 7, adsorbing the end plug seat 6 by the electrode rod 7 through negative pressure, installing a cladding tube 8 on a clamping part of a pneumatic actuating mechanism, and keeping the end part flush.

And 2, moving the pneumatic actuating mechanism to the welding chamber 9, measuring the moving displacement of the cladding tube 8 by using a displacement sensor, and clamping the cladding tube 8 by using a cladding tube clamp 70 when the pneumatic actuating mechanism moves to the welding position.

And 3, controlling the servo motor by the controller to enable the upsetting electric cylinder 1 to move towards one side of the welding chamber 9 until the end plug seat 6 enters a preset position in the welding chamber 9.

And 4, inflating the sealing ring on one side of the cladding tube 8, inflating the sealing ring on one side of the electrode rod 7, after a period of time, pumping out air in the welding chamber 9 by using an air pumping hole at the top of the welding chamber 9, and after a period of time, filling protective atmosphere with certain air pressure into the welding chamber 9.

And 5, controlling a welding power supply to electrify the electrode rod 7 and the welding electrode 50 by the controller, controlling the servo motor to continuously provide power for upsetting to the right side, and mastering the welding quality and adjusting the welding mode in real time through the pressure sensor and the displacement sensor in the execution process.

The further proposal is that the protective atmosphere is low-pressure helium which is not more than 15 MPa.

In a further aspect, the welding power supply has two control modes, a constant current control mode and a constant power control mode.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.