Double hydraulic cylinder lifting device and its control system

Abstract

The present invention discloses a double hydraulic cylinder lifting device and a control system thereof, the device comprises two active lifting cylinder mechanisms and a slave lifting cylinder mechanism of the same structure, the active lifting cylinder mechanism and the slave lifting cylinder mechanism both comprise a support frame and a mounting platform, the support frame comprises an upper mounting seat and a lower mounting seat, the upper mounting seat and the lower mounting seat are connected by a plurality of columns to form a frame structure; a hydraulic cylinder is mounted on the mounting platform, the piston rod of the hydraulic cylinder is connected to a grabbing mechanism by transmission; a plurality of retractable guide rods are also arranged between the upper mounting seat and the lower mounting seat, a follower frame is arranged below the guide rod, the guide rod can synchronously drive the follower frame to move up and down under the action of the hydraulic cylinder; a displacement sensor for monitoring the displacement of the hydraulic cylinder piston rod is also arranged on the support frame. The present invention can realize the telescopic control of the hydraulic cylinder, can make the active hydraulic cylinder and the slave hydraulic cylinder always keep synchronous movement, and complete the stable lifting and lowering action of the load.

Description

Technical Field

[0001] The present invention relates to the technical field of lifting devices, and in particular to a double hydraulic cylinder lifting device and a control system thereof. Background Art

[0002] The automatic demoulding process of the pill press requires the lifting and lowering of the mold load, which places high demands on the safety and stability of the lifting device. At the same time, it is required that after the mold load is lifted, there should be space below it for other devices to pass through. It is planned to use a double hydraulic cylinder lifting device to complete the lifting and lowering of the mold load.

[0003] However, the existing dual hydraulic cylinder lifting device generally adopts an integrated design, and the relative positions of the two hydraulic cylinder mechanisms are fixed. When the load size or installation space changes, it needs to be redesigned, which has poor versatility, and the synchronization accuracy of the two hydraulic cylinders is low, and the stability and reliability are poor. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a dual hydraulic cylinder lifting device and its control system, which can realize the extension and retraction control of the hydraulic cylinder, enable the active hydraulic cylinder and the driven hydraulic cylinder to always maintain synchronous movement, improve the synchronization accuracy, and complete the stable lifting and lowering of the load.

[0005] To achieve the above-mentioned purpose, a dual hydraulic cylinder lifting device designed by the present invention adopts a split structural design, including two active lifting cylinder mechanisms and a slave lifting cylinder mechanism of the same structure, the active lifting cylinder mechanism and the slave lifting cylinder mechanism both include a support frame and a mounting platform arranged above the support frame, the support frame has an upper mounting seat and a lower mounting seat, and the upper mounting seat and the lower mounting seat are connected by a plurality of columns to form a frame structure;

[0006] A hydraulic cylinder is installed on the mounting platform, and a piston rod at the driving end of the hydraulic cylinder penetrates the mounting platform and is transmission-connected to a grabbing mechanism arranged above the mounting platform;

[0007] A plurality of retractable guide rods are also arranged between the upper mounting seat and the lower mounting seat, a follower frame fixedly connected to the guide rod is arranged below the guide rod, the top end of the guide rod passes through the upper mounting seat and is synchronously transmitted with the driving end piston rod of the hydraulic cylinder; the guide rod can synchronously drive the follower frame to move up and down under the action of the hydraulic cylinder; a displacement sensor is also arranged on the support frame, and the displacement sensor is used to monitor the displacement of the piston rod of the hydraulic cylinder.

[0008] Furthermore, rollers are respectively arranged at the four corners of the follower frame, and the follower frame is rollingly connected to the columns located on the same side through the rollers. An induction magnetic ring seat is also arranged on the follower frame.

[0009] Furthermore, the displacement sensor includes an induction magnetic ring and a magnetic scale. The induction magnetic ring is mounted on the induction magnetic ring seat of the follower frame. One end of the magnetic scale is mounted on the upper mounting seat, and the other end extends downward through the induction magnetic ring and is connected to the lower mounting seat.

[0010] Furthermore, a heightening column is provided between the driving end piston rod of the hydraulic cylinder and the gripping mechanism; the driving end piston rod of the hydraulic cylinder is connected to the heightening column via a mounting flange.

[0011] Furthermore, the gripping mechanism includes a pressing plate, a V-shaped claw and an adjustment plate. The V-shaped claw is installed on the heightening column through the pressing plate and the adjustment plate. The pressing plate can drive the V-shaped claw to move along the adjustment plate to adjust its installation position. A plurality of adjustment holes are designed on the adjustment plate. The pressing plate and the adjustment holes are detachably connected through a connecting piece. The pressing plate can move the connection position of the adjustment holes along the adjustment plate to adjust the relative position of the two to adjust the installation position of the V-shaped claw.

[0012] The V-shaped claws of the active lifting cylinder mechanism and the slave lifting cylinder mechanism jointly load the mold through a connecting rod, and the grabbing mechanism can drive the loaded mold to move up and down under the drive of the hydraulic cylinders of the active lifting cylinder mechanism and the slave lifting cylinder mechanism.

[0013] Furthermore, the active lifting cylinder mechanism and the driven lifting cylinder mechanism are both installed and fixed to a steel plate reserved on the foundation via a mounting platform, and the mounting platform is connected to the steel plate reserved on the foundation via a plurality of fasteners.

[0014] The present invention also provides a control system of the above-mentioned dual hydraulic cylinder lifting device, which is used to control the synchronous movement of an active lifting cylinder mechanism and a slave lifting cylinder mechanism, wherein the active lifting cylinder mechanism has an active hydraulic cylinder and a first displacement sensor, and the slave lifting cylinder mechanism has a slave hydraulic cylinder and a second displacement sensor, including a motor, a one-way quantitative pump, a relief valve, a one-way valve, a first servo valve, a second servo valve, a first balancing valve, a second balancing valve, a first PID control module, a second PID control module and a cooler;

[0015] The driving end of the motor is connected to the one-way quantitative pump in a transmission manner, the outlet of the one-way quantitative pump is connected to the inlet of the one-way valve, the overflow valve is arranged on the connecting pipeline between the one-way quantitative pump and the one-way valve, and the cooler is connected to the connecting pipeline between the one-way quantitative pump and the overflow valve; the inlet of the one-way quantitative pump is connected to the oil tank, the outlet of the one-way quantitative pump is connected to the P port of the first servo valve and the second servo valve after the one-way valve, and the T port of the first servo valve and the second servo valve is connected to the oil tank;

[0016] The A and B ports of the first servo valve are respectively connected to the rodless cavity and the rod cavity of the active hydraulic cylinder through the first balance valve; the first displacement sensor is used to monitor the displacement of the active hydraulic cylinder, and the signal output end of the first displacement sensor is respectively connected to the signal input ends of the first PID control module and the second PID control module;

[0017] The A and B ports of the second servo valve are respectively connected to the rodless cavity and the rod cavity of the driven hydraulic cylinder through the second balance valve, the second displacement sensor is used to monitor the displacement of the driven hydraulic cylinder, and the signal output end of the second displacement sensor is connected to the signal input end of the second PID control module.

[0018] Furthermore, the control system of the double hydraulic cylinder lifting device further includes a trajectory planning module, and the trajectory planning module plans the motion trajectory of the active hydraulic cylinder according to the set target position, target speed, and acceleration and deceleration time; the position set value of the active hydraulic cylinder is given by the output value of the trajectory planning module, the position feedback value is obtained by the first displacement sensor, the position set value and the position feedback value are compared and processed by the first PID control module, and the analog signal obtained after the output value is D / A converted controls the spool displacement of the first servo valve to achieve the smooth start and in-place stop of the active hydraulic cylinder.

[0019] Still further, for the position closed-loop control of the driven hydraulic cylinder, the position set value of the driven hydraulic cylinder is obtained by the first displacement sensor, the position feedback value is obtained by the second displacement sensor, the position set value and the position feedback value are compared and processed by the second PID control module, and the analog signal obtained after the output value is D / A converted is used to control the spool displacement of the second servo valve, so as to achieve the synchronous control of the active hydraulic cylinder and the driven hydraulic cylinder.

[0020] Even further, both the first servo valve and the second servo valve adopt three-position four-way servo valves to achieve the telescopic control of the active hydraulic cylinder and the driven hydraulic cylinder. The center position function is Y type. When the spool is in the center position, the hydraulic control pressures of the first balance valve and the second balance valve connected to the active hydraulic cylinder and the driven hydraulic cylinder are zero, ensuring that the first balance valve and the second balance valve are in the closed state, so as to ensure that when the system stops, the active hydraulic cylinder and the driven hydraulic cylinder maintain their current positions.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] First, the lifting device of the present invention adopts a split design, which is convenient for installation and is not restricted by the installation space.

[0023] Second, the lifting device of the present invention is installed and fixed by several bolts between the installation platform and the reserved steel plate of the foundation, that is, only the actuator is located above the ground, and other parts are located in the pit, and the explosion-proof safety is better.

[0024] Thirdly, the lifting cylinder mechanism of the present invention adopts a modular design, and the V-shaped claws can be designed and replaced according to the interfaces of loads to adapt to different load interfaces.

[0025] Fourthly, except for the hydraulic cylinder, the moving parts of other lifting cylinder components of the lifting cylinder mechanism of the present invention are isolated by copper parts to prevent the generation of sparks, and it is applicable to environments with high safety requirements such as dust explosion.

[0026] Fifthly, the control system of the present invention uses a servo valve as the flow regulating valve of the hydraulic cylinder, with a faster response speed and can avoid the generation of zero-position dead zones.

[0027] Sixthly, the control system of the present invention can ensure the smooth start and stop of the hydraulic cylinder, plan the movement trajectory of the active hydraulic cylinder, and combine with the fuzzy PID control algorithm to achieve the smooth start and in-place stop of the hydraulic cylinder; at the same time, limit the minimum opening of the servo valve during the deceleration process to ensure that the hydraulic cylinder does not generate a "crawling" phenomenon.

[0028] Seventhly, the control system of the present invention uses a displacement sensor as the displacement feedback of the hydraulic cylinder. By obtaining the displacement deviation values of the active hydraulic cylinder and the driven hydraulic cylinder, and combining with the fuzzy PID control algorithm to compensate for the displacement deviation, the active hydraulic cylinder and the driven hydraulic cylinder can always maintain synchronous movement, improving the lifting synchronization accuracy.

[0029] Eighthly, the present invention is applicable to the process of pressing and demolding drugs. The lifting and lowering actions are stable, and the position synchronization accuracy can reach below 0.5 mm. The grasping mechanism can be improved and applied to the synchronous movement of other types of loads. Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of the active lifting cylinder mechanism of a double-hydraulic-cylinder lifting device;

[0031] Figure 2 is Figure 1 front view structural diagram;

[0032] Figure 3 is Figure 1 side view structural diagram;

[0033] Figure 4 is a schematic diagram of the control system of the double-hydraulic-cylinder lifting device;

[0034] In the figure: support frame 1 (upper mounting seat 1.1, lower mounting seat 1.2, column 1.3), mounting platform 2, hydraulic cylinder 3, grasping mechanism 4 (pressing plate 4.1, V-claw 4.2, adjusting plate 4.3), guide rod 5, follower frame 6 (roller 6.1, induction magnetic ring seat 6.2), displacement sensor 7, induction magnetic ring 8, magnetic scale 9, heightening column 10, mounting flange 11, motor 12, one-way quantitative pump 13, overflow valve 14, one-way valve 15, first servo valve 16, second servo valve 17, first balancing valve 18, second balancing valve 19, first PID control module 20, second PID control module 21, connecting rod 22, cooler 23, trajectory planning module 24. DETAILED DESCRIPTION

[0035] The following is a detailed description of the implementation of the present invention in conjunction with the implementation cases, but they do not constitute a limitation of the present invention and are only given as examples. At the same time, the advantages of the present invention will become clearer and easier to understand through the description.

[0036] like Figures 1 to 3 A double hydraulic cylinder lifting device shown in the figure includes two active lifting cylinder mechanisms and a slave lifting cylinder mechanism of the same structure, and the active lifting cylinder mechanism and the slave lifting cylinder mechanism are installed in a mirror image. The active lifting cylinder mechanism and the slave lifting cylinder mechanism both include a support frame 1 and a mounting platform 2 arranged above the support frame 1, and the support frame 1 has an upper mounting seat 1.1 and a lower mounting seat 1.2, and the upper mounting seat 1.1 and the lower mounting seat 1.2 are connected by four columns 1.3 to form a frame structure; a hydraulic cylinder 3 is installed on the mounting platform 2, and the driving end piston rod of the hydraulic cylinder 3 passes through the mounting platform 2 and is transmission-connected to the grasping mechanism 4 arranged above it; two retractable guide rods 5 are also arranged between the upper mounting seat 1.1 and the lower mounting seat 1.2, and a guide rod 5 is arranged below the guide rod 5. The top of the guide rod 5 is connected to the follower frame 6, and the top of the guide rod 5 passes through the upper mounting seat 1.1 and is rigidly connected to the driving end piston rod of the hydraulic cylinder 3 through the mounting flange for synchronous transmission. The guide rod 5 can synchronously drive the follower frame 6 to move up and down under the action of the hydraulic cylinder 3; each hydraulic cylinder is equipped with two guide rods 5, and a copper bushing is installed in the rod sleeve. The head of the guide rod 5 is rigidly connected to the head of the piston rod of the hydraulic cylinder through the mounting flange. The mounting flange can drive the guide rod 5 to move up and down relative to the mounting platform 2 under the drive of the hydraulic cylinder piston rod to improve the movement rigidity of the hydraulic cylinder and prevent the piston rod from rotating. A displacement sensor 7 is also provided on the support frame 1, and the displacement sensor 7 is used to monitor the displacement of the piston rod of the hydraulic cylinder 3.

[0037] The follower frame 6 is fixed to the lower part of the guide rod 5 and moves synchronously with the guide rod 5 and the piston rod of the hydraulic cylinder 3; copper rollers 6.1 are installed at the four corners of the follower frame 6 and can roll along the four columns 1.3 of the support frame 1; an induction magnetic ring seat 6.2 is also arranged on the side of the follower frame 6.

[0038] In this embodiment, the displacement sensor 7 is a magnetic grating displacement sensor with an accuracy of up to ±0.01 mm. Compared with grating scales and wire-drawing displacement sensors, it has good water, oil, dust and vibration resistance, strong environmental adaptability and a long service life. The displacement sensor 7 includes an induction magnetic ring 8 and a magnetic scale 9. The induction magnetic ring 8 is installed on the induction magnetic ring seat 6.2 of the follower frame 6. One end of the magnetic scale 9 is installed on the upper mounting seat 1.1, and the other end extends downward through the induction magnetic ring 8 and is connected to the lower mounting seat 1.2, which can provide real-time feedback on the displacement of the hydraulic cylinder piston rod.

[0039] A heightening column 10 is also provided between the driving end piston rod of the hydraulic cylinder 3 and the grasping mechanism 4. The lifting cylinder mechanism is installed in a way that part of it is underground and part of it is above ground. The installation platform 2 is used for the installation of the lifting cylinder mechanism and can be fixedly connected to the steel plate reserved on the foundation.

[0040] The grasping mechanism 4 includes a pressing plate 4.1, a V-shaped claw 4.2 and an adjustment plate 4.3. The V-shaped claw 4.2 is installed on the heightening column 10 through the pressing plate 4.1 and the adjustment plate 4.3. The pressing plate 4.1 can drive the V-shaped claw 4.2 to move along the adjustment plate 4.3 to adjust its installation position. A number of adjustment holes are designed on the adjustment plate. The pressing plate and the adjustment holes are detachably connected through connecting parts (such as bolts). The pressing plate can move along the adjustment plate to adjust the connection position of the adjustment holes, thereby adjusting their relative positions to adjust the installation position of the V-shaped claw. The V-shaped claws 4.2 of the active lifting cylinder mechanism and the driven lifting cylinder mechanism jointly carry the mold through a connecting rod 22. The grasping mechanism 4 can drive the loaded mold to move up and down under the drive of the hydraulic cylinders 3 of the active lifting cylinder mechanism and the driven lifting cylinder mechanism. The V-shaped claw 4.2 can be designed and replaced according to the interface of the mold to adapt to different mold interfaces. The use of the V-shaped claw 4.2 design can automatically adjust the circumferential position deviation when placing the mold during the lifting process, facilitating alignment with the lifting target. The V-shaped claw 4.2 is connected to the heightening column 10 by an installation flange, which is convenient for replacing different types of V-shaped claws 4.2. The heightening column 10 is designed with head and tail flanges, which is also convenient for replacing heightening columns of different heights. The output interface of the hydraulic cylinder piston rod is also connected by an installation flange 11, which is convenient for connection with different actuator ends.

[0041] Such as Figure 4As shown, the control system of the double hydraulic cylinder lifting device of the present invention is used to control the synchronous movement of the active lifting cylinder mechanism and the slave lifting cylinder mechanism, the active lifting cylinder mechanism has an active hydraulic cylinder 3.1 and a first displacement sensor 7.1, the slave lifting cylinder mechanism has a slave hydraulic cylinder 3.2 and a second displacement sensor 7.2, and the control system of the double hydraulic cylinder lifting device includes a motor 12, a one-way quantitative pump 13, a relief valve 14, a one-way valve 15, a first servo valve 16, a second servo valve 17, a first balancing valve 18, a second balancing valve 19, a first PID control module 20, a second PID control module 21, a trajectory planning module 24 and a cooler 23;

[0042] The driving end of the motor 12 is connected to the one-way metering pump 13 in a transmission manner, the outlet of the one-way metering pump is connected to the inlet of the one-way valve 15, the overflow valve 14 is arranged on the connecting pipeline between the one-way metering pump 13 and the one-way valve 15, and the cooler 23 is connected to the connecting pipeline between the one-way metering pump 13 and the overflow valve 14; the inlet of the one-way metering pump 13 is connected to the oil tank, the outlet of the one-way metering pump 13 is connected to the P port of the first servo valve 16 and the second servo valve 17 after the one-way valve 15, and the T port of the first servo valve 16 and the second servo valve 17 is connected to the oil tank;

[0043] The A and B ports of the first servo valve 16 are respectively connected to the rodless chamber and the rod chamber of the active hydraulic cylinder 3.1 through the first balance valve 18; the first displacement sensor 7.1 is used to monitor the displacement of the active hydraulic cylinder 3.1, and the signal output end of the first displacement sensor 7.1 is respectively connected to the signal input end of the first PID control module 20 and the second PID control module 21;

[0044] The A and B ports of the second servo valve 17 are respectively connected to the rodless chamber and the rod chamber of the slave hydraulic cylinder 3.2 through the second balancing valve 19. The second displacement sensor 7.2 is used to monitor the displacement of the slave hydraulic cylinder 3.2. The signal output end of the second displacement sensor 7.2 is connected to the signal input end of the second PID control module 21.

[0045] The trajectory planning module 24 plans the motion trajectory of the active hydraulic cylinder 3.1 according to the target position, target speed, acceleration and deceleration time set by the host computer; the position given value of the active hydraulic cylinder 3.1 is given by the output value of the trajectory planning module 24, and the position feedback value is obtained by the first displacement sensor 7.1. The position given value and the position feedback value are compared and processed by the first PID control module 20. The analog signal obtained after the output value is converted by D / A controls the valve core displacement of the first servo valve 16, so as to realize the smooth start and stop of the active hydraulic cylinder 3.1.

[0046] Position closed-loop control of the slave hydraulic cylinder 3.2. The position set value of the slave hydraulic cylinder 3.2 is obtained by the first displacement sensor 7.1, and the position feedback value is obtained by the second displacement sensor 7.2. The position set value and the position feedback value are compared and processed by the second PID control module 21. The analog signal obtained after the output value is D / A converted is used to control the spool displacement of the second servo valve 17, so as to realize the synchronous control of the master hydraulic cylinder 3.1 and the slave hydraulic cylinder 3.2.

[0047] Both the first servo valve 16 and the second servo valve 17 adopt three-position four-way servo valves to realize the telescopic control of the master hydraulic cylinder 3.1 and the slave hydraulic cylinder 3.2. The neutral position function is Y type. When the spool is in the neutral position, the hydraulic control pressures of the first balance valve 18 and the second balance valve 19 connected to the master hydraulic cylinder 3.1 and the slave hydraulic cylinder 3.2 are zero, ensuring that the first balance valve 18 and the second balance valve 19 are in the closed state, so as to ensure that when the system stops, the master hydraulic cylinder 3.1 and the slave hydraulic cylinder 3.2 maintain their current positions.

[0048] When the temperature of the hydraulic oil exceeds the normal working range of the hydraulic oil, the change in the viscosity of the hydraulic oil affects the stability of the hydraulic control system. During normal operation, the oil temperature is controlled by the cooler 23. When the oil temperature rises to the set temperature, the cooler 23 works. When the temperature drops to the set temperature, the cooler 23 stops, so as to keep the oil temperature within a suitable temperature range.

[0049] The PID control module of the control system of the present invention uses a fuzzy PID algorithm to compensate for the displacement deviation, so as to realize that the master hydraulic cylinder and the slave hydraulic cylinder always maintain synchronous movement. The control system has the functions of synchronous position over-tolerance and timeout alarm and processing: when the position synchronization of the double hydraulic cylinders is over-tolerant (exceeding 2 mm) or the time taken to reach the target position exceeds the set time, the controller controls the sound and light alarm to give an abnormal alarm, closes the servo valve, stops the movement of the hydraulic cylinder, and at the same time feeds back the alarm information to the host computer for manual troubleshooting. The control system has a debugging function: a separate telescopic debugging function for each hydraulic cylinder.

[0050] The controller includes a trajectory planning module, a first PID control module, and a second PID control module. The host computer is connected to the controller through Ethernet for functions such as parameter setting, operating state display, and control instruction sending. The controller reserves an Ethernet communication interface and has the function of working in cooperation with other devices.

[0051] The above is only the specific implementation manner of the present invention. It should be noted that any change or replacement that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. The rest not described in detail is the prior art.

Claims

1. A double hydraulic cylinder lifting device, characterized in that: It includes two active lifting cylinder mechanisms and a driven lifting cylinder mechanism with the same structure. Both the active lifting cylinder mechanism and the driven lifting cylinder mechanism include a support frame (1) and a mounting platform (2) arranged above the support frame (1). The support frame (1) has an upper mounting seat (1.1) and a lower mounting seat (1.2). A frame structure is formed by connecting the upper mounting seat (1.1) and the lower mounting seat (1.2) through a number of columns (1.3). A hydraulic cylinder (3) is mounted on the mounting platform (2). The driving end piston rod of the hydraulic cylinder (3) penetrates through the mounting platform (2) and is in transmission connection with a grasping mechanism (4) arranged above it. A number of telescopic guide rods (5) are also arranged between the upper mounting seat (1.1) and the lower mounting seat (1.2). A follower frame (6) fixedly connected with the guide rod (5) is arranged below the guide rod (5). The top end of the guide rod (5) penetrates through the upper mounting seat (1.1) and is in synchronous transmission connection with the driving end piston rod of the hydraulic cylinder (3). The guide rod (5) can drive the follower frame (6) to move up and down synchronously under the action of the hydraulic cylinder (3). A displacement sensor (7) is also arranged on the support frame (1). The displacement sensor (7) is used to monitor the displacement of the piston rod of the hydraulic cylinder (3). A heightening column (10) is also arranged between the driving end piston rod of the hydraulic cylinder (3) and the grasping mechanism (4). The driving end piston rod of the hydraulic cylinder (3) is connected with the heightening column (10) through a mounting flange (11). The grasping mechanism (4) includes a pressing plate (4.1), a V-shaped claw (4.2) and an adjusting plate (4.3). The V-shaped claw (4.2) is mounted on the heightening column (10) through the pressing plate (4.1) and the adjusting plate (4.3). The pressing plate (4.1) can drive the V-shaped claw (4.2) to move along the adjusting plate (4.3) to adjust its mounting position. The V-shaped claws (4.2) of the active lifting cylinder mechanism and the driven lifting cylinder mechanism jointly carry a mold through a connecting rod (22). The grasping mechanism (4) can drive the loaded mold to move up and down under the drive of the hydraulic cylinders (3) of the active lifting cylinder mechanism and the driven lifting cylinder mechanism.

2. The double hydraulic cylinder lifting device according to claim 1, characterized in that: Rollers (6.1) are respectively arranged at the four corners of the follower frame (6). The follower frame (6) is in rolling connection with the column (1.3) on the same side through the rollers (6.1). An induction magnetic ring seat (6.2) is also arranged on the follower frame (6).

3. The double hydraulic cylinder lifting device according to claim 2, wherein: The displacement sensor (7) includes an induction magnetic ring (8) and a magnetic scale (9). The induction magnetic ring (8) is mounted on the induction magnetic ring seat (6.2) of the follower frame (6). One end of the magnetic scale (9) is mounted on the upper mounting seat (1.1), and the other end extends downward through the induction magnetic ring (8) and is connected with the lower mounting seat (1.2).

4. The double hydraulic cylinder lifting device according to claim 1 or 2 or 3, characterized in that: Both the active lifting cylinder mechanism and the driven lifting cylinder mechanism are installed and fixed through the mounting platform (2) and the steel plates reserved on the foundation.

5. A control system for the double hydraulic cylinder lifting device according to any one of claims 1 to 4, which is used to control the synchronous movement of the active lifting cylinder mechanism and the driven lifting cylinder mechanism. The active lifting cylinder mechanism has an active hydraulic cylinder (3.1) and a first displacement sensor (7.1), and the driven lifting cylinder mechanism has a driven hydraulic cylinder (3.2) and a second displacement sensor (7.2), and is characterized in that: It includes a motor (12), a unidirectional fixed-displacement pump (13), a relief valve (14), a check valve (15), a first servo valve (16), a second servo valve (17), a first balance valve (18), a second balance valve (19), a first PID control module (20), a second PID control module (21), and a cooler (23); The driving end of the motor (12) is in transmission connection with the unidirectional fixed-displacement pump (13). The outlet of the unidirectional fixed-displacement pump (13) is connected to the inlet of the check valve (15). The relief valve (14) is arranged on the connecting pipeline between the unidirectional fixed-displacement pump (13) and the check valve (15). The cooler (23) is connected to the connecting pipeline between the unidirectional fixed-displacement pump (13) and the relief valve (14). The inlet of the unidirectional fixed-displacement pump (13) is connected to the fuel tank. The outlet of the unidirectional fixed-displacement pump (13) is connected to the P ports of the first servo valve (16) and the second servo valve (17) via the check valve (15). The T ports of the first servo valve (16) and the second servo valve (17) are connected to the fuel tank; The A and B ports of the first servo valve (16) are respectively connected to the rodless cavity and the rod cavity of the active hydraulic cylinder (3.1) through the first balance valve (18). The first displacement sensor (7.1) is used to monitor the displacement of the active hydraulic cylinder (3.1). The signal output end of the first displacement sensor (7.1) is respectively connected to the signal input ends of the first PID control module (20) and the second PID control module (21); The A and B ports of the second servo valve (17) are respectively connected to the rodless cavity and the rod cavity of the driven hydraulic cylinder (3.2) through the second balance valve (19). The second displacement sensor (7.2) is used to monitor the displacement of the driven hydraulic cylinder (3.2). The signal output end of the second displacement sensor (7.2) is connected to the signal input end of the second PID control module (21).

6. The control system according to claim 5, characterized in that: It further includes a trajectory planning module (24). The trajectory planning module (24) performs motion trajectory planning on the active hydraulic cylinder (3.1) according to the set target position, target speed, and acceleration and deceleration time. Its output value serves as the position set value of the first PID control module (20), and the feedback value of the first displacement sensor (7.1) serves as the position feedback value of the first PID control module (20). The position set value and the position feedback value are compared and processed by the first PID control module (20). The analog signal obtained after the output value is converted by D / A controls the spool displacement of the first servo valve (16) to achieve the smooth start and in-place stop of the active hydraulic cylinder (3.1).

7. The control system according to claim 5, characterized in that: The position closed-loop control of the slave hydraulic cylinder (3.2). The position set value of the slave hydraulic cylinder (3.2) is obtained by the first displacement sensor (7.1), and the position feedback value is obtained by the second displacement sensor (7.2). The position set value and the position feedback value are compared and processed by the second PID control module (21). The analog signal obtained after the output value is D / A converted is used to control the spool displacement of the second servo valve (17), so as to realize the synchronous control of the master hydraulic cylinder (3.1) and the slave hydraulic cylinder (3.2).

8. The control system according to claim 5, wherein: Both the first servo valve (16) and the second servo valve (17) adopt three-position four-way servo valves to realize the telescopic control of the master hydraulic cylinder (3.1) and the slave hydraulic cylinder (3.2). The neutral position function is Y type. When the spool is in the neutral position, the hydraulic control pressures of the first balance valve (18) and the second balance valve (19) connected to the master hydraulic cylinder (3.1) and the slave hydraulic cylinder (3.2) are zero, ensuring that the first balance valve (18) and the second balance valve (19) are in the closed state, and ensuring that the master hydraulic cylinder (3.1) and the slave hydraulic cylinder (3.2) maintain their current positions when the system stops.

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