A plunger rod device for a vacuum induction furnace launder system

Abstract

The application discloses a plunger rod device for a vacuum induction furnace flow channel system, comprising a hydraulic drive assembly, a plunger actuator and a flow channel, wherein the hydraulic drive assembly comprises a hydraulic cylinder, a shaft coupling and a push rod, the hydraulic cylinder is fixed on a mounting flange of a tundish top surface of the flow channel through a sealing base; the tundish is in a vacuum state, the hydraulic cylinder is located outside the tundish of the flow channel and realizes vacuum isolation with the tundish of the flow channel through the sealing base; the extending rod of the hydraulic cylinder is downward, and the end of the extending rod of the hydraulic cylinder is connected with the push rod through the shaft coupling; the plunger actuator comprises a stop flange, a main body support, a rocker arm, a transmission plate, a plunger rod and two lever shafts. The plunger rod device for the vacuum induction furnace flow channel system effectively solves the problems of incomplete sealing of a traditional nozzle for the vacuum induction furnace flow channel system, high maintenance intensity and short service life.

Description

Technical Field

[0001] This invention relates to a plunger rod device for a flow channel system in a vacuum induction furnace. Background Technology

[0002] A vacuum induction furnace is a complete set of vacuum smelting equipment that uses the principle of high-frequency induction heating in a vacuum environment to melt metal. It is also one of the important vacuum smelting equipment in the metallurgical field for producing special alloy materials such as nickel-based high-temperature alloys, nuclear alloys, stainless steel, and ultra-high-strength steel.

[0003] Currently, with the booming development of the steel industry, vacuum induction furnaces are also undergoing rapid development, especially in the field of special steel smelting, where the requirements for the mechanical properties of steel materials are extremely stringent. These materials are often used in cutting-edge high-tech industries such as aerospace and satellite engineering. Therefore, we are diligently researching the performance and structure of vacuum furnaces from various perspectives, including ergonomics, energy efficiency, automation, and environmental protection. In this regard, the hot runner insertion device has received widespread attention in the domestic and international steel and special metallurgical fields for producing high-quality electrodes and reducing slag and inclusions. Currently, vacuum induction melting furnace systems suffer from various drawbacks: easy contamination by gases during casting, low product quality, high production costs, and the risk of metal entering the mold chamber. This is closely related to the current use of long runners with built-in plunger systems or the absence of plunger systems in vacuum induction furnace systems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a plunger rod device for a vacuum induction furnace flow channel system. This device has a good switching and blocking effect on the flow channel, a long service life, and a high degree of automation. It can effectively improve the quality of vacuum-melted products, improve the stability of the material of vacuum-melted products, reduce the labor intensity of workers, improve continuous production efficiency, and achieve energy saving, emission reduction, green and efficient production. It effectively solves the problems of low service life, high maintenance intensity, and low material quality of traditional plunger mechanisms used in vacuum induction furnace vacuum systems.

[0005] The technical solution to achieve the above objective is: a plunger rod device for a flow channel system in a vacuum induction furnace, comprising a hydraulic drive assembly, a plunger actuator, and a flow channel, wherein:

[0006] The hydraulic drive assembly includes a hydraulic cylinder, a coupling, and a push rod. The hydraulic cylinder is fixed to the mounting flange on the top surface of the tundish of the flow channel via a sealing seat. The tundish of the flow channel is in a vacuum state. The hydraulic cylinder is located outside the tundish of the flow channel and is vacuum isolated from the tundish of the flow channel through the sealing seat. The extension rod of the hydraulic cylinder points downward, and the end of the extension rod of the hydraulic cylinder is connected to a push rod via a coupling.

[0007] The plunger actuator includes a stop flange, a main support, a rocker arm, a transmission plate, a plunger rod, and two lever shafts. The main support is fixed to the side wall of the flow channel by a mounting bracket. The main support has vertically formed guide holes for the support column and two sets of guide holes for the lever shafts. The stop flange consists of a bearing flange and a support column connected to its bottom end. The support column is vertically movable and inserted into the guide holes of the support column. The stop flange is located directly below the push rod, and the push rod is coaxial with the support column. The two lever shafts... The rocker arm is inserted into the guide holes of the two sets of lever shafts, and each lever shaft moves up and down along the corresponding guide hole; the middle part of the rocker arm is rotatably set at the bottom end of the main support through a pin, and the rocker arm rotates and reciprocates around the pin; one end of the rocker arm is connected to the bottom end of the support column, and the other end is connected to the bottom end of the two lever shafts respectively; one end of the transmission plate is connected to the top end of the two lever shafts respectively, and the other end is connected to the top end of the plunger rod, and the plunger rod is aligned with the pouring nozzle of the flow channel.

[0008] The aforementioned plunger rod device for a vacuum induction furnace flume system comprises two rod arm shafts arranged parallel to each other, with a counterweight connected to the bottom end of each rod arm shaft.

[0009] The aforementioned plunger rod device for a vacuum induction furnace flute system includes a ceramic tip at the bottom end of the plunger rod.

[0010] The aforementioned plunger rod device for a vacuum induction furnace flume system includes a U-shaped groove at one end of the transmission plate, the top end of the plunger rod being disposed within the U-shaped groove and adjustable back and forth along the U-shaped groove, and the plunger rod being coaxial with the pouring nozzle of the flume.

[0011] In the aforementioned plunger rod device for a vacuum induction furnace flute system, a sealing ring is provided between the contact surface of the hydraulic cylinder and the sealing seat.

[0012] The aforementioned plunger rod device for a vacuum induction furnace flute system, wherein the bearing flange of the stop flange is made of graphite bronze.

[0013] In the aforementioned plunger rod device for a vacuum induction furnace flute system, during pouring, the hydraulic cylinder drives the push rod downward via a coupling, striking the bearing flange of the stop flange. The support column of the stop flange moves downward, and during the downward movement of the support column, the rocker arm drives the two rod arms to move axially upward, which in turn drives the plunger rod upward via a transmission plate, moving it away from the pouring nozzle of the flute. When pouring stops, the hydraulic cylinder drives the push rod to retract via the coupling, stopping the pressure applied to the stop flange. The plunger actuator returns to its initial state, and the plunger rod moves downward under gravity to block the pouring nozzle of the flute.

[0014] The aforementioned plunger rod device for a vacuum induction furnace flume system, wherein the hydraulic drive assembly further includes a first electromagnetic directional valve, the first electromagnetic directional valve being provided with a first hydraulic interface and a second hydraulic interface.

[0015] The hydraulic cylinder includes an upper cylinder chamber, a piston, and a lower cylinder chamber. The upper cylinder chamber is provided with an upper hydraulic port, and the lower cylinder chamber is provided with a lower hydraulic port.

[0016] The upper hydraulic port of the upper cylinder chamber is connected to the first hydraulic port of the first electromagnetic directional valve through the upper reciprocating air path; the lower hydraulic port of the lower cylinder chamber is connected to the second hydraulic port of the first electromagnetic directional valve through the lower reciprocating air path.

[0017] The first electromagnetic directional valve communicates with the hydraulic controller, which controls the direction of movement of the hydraulic cylinder by controlling the first electromagnetic directional valve.

[0018] The aforementioned plunger rod device for a vacuum induction furnace flume system further includes a bladder accumulator. The outlet of the bladder accumulator is connected to the upper and lower reciprocating air paths of the hydraulic cylinder via a second electromagnetic directional valve. The outlet of the bladder accumulator is flow-controlled via a throttle valve. The bladder accumulator is switched on and off via a manual plate ball valve. The second electromagnetic directional valve communicates with a hydraulic controller, which controls whether the bladder accumulator is used for operation by controlling the second electromagnetic directional valve.

[0019] The aforementioned plunger rod device for a vacuum induction furnace flume system further includes a third electromagnetic directional valve. The upper cylinder chamber is equipped with an upper proximity switch, and the lower cylinder chamber is equipped with a lower proximity switch. The third electromagnetic directional valve is connected to both the upper and lower reciprocating air paths. The third electromagnetic directional valve has a first control signal terminal corresponding to the upper reciprocating air path interface and a second control signal terminal corresponding to the lower reciprocating air path interface. The upper proximity switch, the lower proximity switch, the first control signal terminal, and the second control signal terminal all communicate with a hydraulic controller via signal terminals. The hydraulic controller controls the third electromagnetic directional valve to switch the entire hydraulic drive assembly on and off.

[0020] The plunger rod device for a vacuum induction furnace casting system of the present invention has a hydraulic actuator whose push rod is coaxially fixed to the stop flange in the plunger actuator. The hydraulic cylinder is located outside the tundish and is vacuum-sealed using a sealing seat. The plunger actuator is fixed to the side of the casting channel body by bearings and transmits motion and changes the direction of motion through a bottom rocker arm. Finally, the plunger rod blocks the casting nozzle of the casting channel when it descends, achieving a closing effect. The plunger actuator ensures vertical up-and-down movement through a guide hole. Its principle is that the hydraulic cylinder switches the plunger rod at the opening and closing of the casting channel nozzle, controlling the entry of molten metal into the ingot chamber to achieve the predetermined process effect. At the same time, the design of the casting channel length uses a shorter casting channel structure while maintaining the slag-blocking function to achieve a lower casting superheat and prevent the freezing of steel. This design effectively improves the quality of vacuum-melted products, enhances the stability of vacuum-melted product materials, reduces the labor intensity of workers, increases continuous production efficiency, and achieves energy conservation, emission reduction, and green efficiency. It effectively solves the problems of low service life, high maintenance intensity, and low material quality of traditional plunger mechanisms used in vacuum induction furnace vacuum systems. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the plunger rod device for the flow channel system of a vacuum induction furnace according to the present invention;

[0022] Figure 2 This is the electrical schematic diagram of a hydraulic cylinder. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, its specific embodiments are described in detail below with reference to the accompanying drawings:

[0024] Please see Figure 1 and Figure 2 According to the preferred embodiment of the present invention, a plunger rod device for a flow channel system of a vacuum induction furnace includes a hydraulic drive assembly A, a plunger actuator B, and a flow channel C.

[0025] The hydraulic drive assembly A includes a hydraulic cylinder 1, a coupling 4, and a push rod 5. The hydraulic cylinder 1 is fixed to the mounting flange 3 on the top surface of the tundish of the flow channel C via a sealing seat 2. A sealing ring is provided between the contact surfaces of the hydraulic cylinder 1 and the sealing seat 2.

[0026] The intermediate liner of the flow channel C is in a vacuum state. The hydraulic cylinder 1 is located outside the intermediate liner of the flow channel C and is vacuum isolated from the intermediate liner of the flow channel C through the sealing seat 2. The extension rod of the hydraulic cylinder 1 is pointing downwards, and the end of the extension rod of the hydraulic cylinder 1 is connected to the push rod 5 through the coupling 4.

[0027] The plunger actuator B includes a stop flange 6, a main support 7, a rocker arm 8, a transmission plate 12, a plunger rod 13, and two lever shafts 11. The main support 7 is fixed to the side wall of the flow channel C by a mounting bracket 10. The main support 7 has vertically formed guide holes for the support column and two sets of guide holes for the lever shafts. The entire plunger actuator C can be adjusted horizontally left and right using bearings and bolts on the mounting bracket 10, and is finally fixed in position by locking screws on the mounting bracket 10.

[0028] The stop flange 6 consists of a bearing flange and a support column connected to its bottom end. The bearing flange at the top is made of graphite bronze, which has high load-bearing capacity to improve the service life of the mechanism. The support column can be inserted into the support column guide hole, which can move up and down. The stop flange 6 is located directly below the push rod 5, and the push rod 5 is coaxial with the support column to improve mechanical performance. The push rod 5 is equivalent to extending the extension rod of the hydraulic cylinder 1. When the extension rod of the hydraulic cylinder 1 extends, it can transmit the motion to the stop flange 6 through the push rod 5. The support column can only make vertical reciprocating movements along the support column guide hole.

[0029] Two lever shafts 11 are inserted into two sets of lever shaft guide holes in a one-to-one correspondence, and each lever shaft 11 moves up and down reciprocally along the corresponding lever shaft guide hole. The two lever shafts 11 are arranged parallel to each other, and the bottom ends of the two lever shafts 11 are connected to a counterweight 9. This counterweight has two functions: first, to ensure that the two lever shafts 11 can move synchronously; second, to counteract the buoyancy of the liquid metal in the flow channel C by adjusting the counterweight, so as to ensure the sealing effect of the plunger rod 13 on the pouring nozzle 14.

[0030] The middle part of the rocker arm 8 is rotatably mounted at the bottom of the main support 7 via a pin. The rocker arm 8 rotates and reciprocates around the pin. One end of the rocker arm 8 is connected to the bottom of the support column, and the other end is connected to the bottom of the two lever shafts 11 respectively. Through this rocker arm 8, the vertical movement direction of the stop flange 6 can be transmitted in the opposite direction to the lever shafts 11. When the stop flange 6 moves downward, the lever shaft 11 moves upward; conversely, when the stop flange 6 moves upward, the lever shaft 11 moves downward.

[0031] One end of the transmission plate 12 is connected to the top of the two lever shafts 11, and the other end is connected to the top of the plunger rod 13, which is aligned with the pouring nozzle 14 of the flow channel.

[0032] The transmission plate 12 and the lever arm shaft 11 can move up and down synchronously. A U-shaped groove is opened at the other end of the transmission plate 12. The U-shaped groove is used to install the plunger rod 13. The installation position of the plunger rod 13 can be adjusted back and forth along the U-shaped groove. The ultimate goal is to align the plunger rod 13 with the pouring nozzle of the flow channel and keep them coaxial. By using the plunger rod 13 to seal the pouring nozzle 14, the purpose of preventing molten metal from entering the mold chamber can be achieved.

[0033] The bottom end of the plunger rod 13 has a ceramic tip to facilitate sealing of the pouring nozzle 14.

[0034] The plunger rod device for the flow channel system of a vacuum induction furnace of the present invention, during pouring, the hydraulic cylinder 1 drives the push rod 5 to move downward through the coupling 4, striking the bearing flange of the stop flange 6. The support column of the stop flange 6 moves downward. During the downward movement of the support column, the rocker arm 8 drives the two rod arm shafts 11 to move upward simultaneously, and then drives the plunger rod 13 to move upward through the transmission plate 12, away from the pouring nozzle 14 of the flow channel C, so that the molten metal in the flow channel C can enter the mold chamber for the next process. When pouring stops, the hydraulic cylinder 1 drives the push rod 5 to retract through the coupling 4, stopping the pressure applied to the stop flange 6. The plunger actuator returns to its initial state, and the plunger rod 13 moves downward under the action of gravity to block the pouring nozzle 14 of the flow channel C, preventing the molten metal from entering the mold chamber.

[0035] The plunger rod device for the trough system of a vacuum induction furnace of the present invention allows the entire plunger actuator C to be adjusted horizontally by bearings and bolts on the mounting bracket 10. Simultaneously, the plunger rod 13 can be adjusted forward and backward by the U-shaped groove on the transmission plate 12 to increase the sealing performance of the pouring nozzle 14 of the trough C. The length of the trough C is designed to be as short as possible to achieve two main objectives: effectively removing large-sized slag and achieving a low pouring superheat (which reduces nitrogen solubility and nitride inclusions) while preventing frozen steel. In this embodiment,

[0036] Unless acted upon by the hydraulic cylinder, the plunger rod 13 remains in contact with the pouring nozzle 14 of the flow channel C. If the plunger rod 13 is stuck in the open position, the tundish of the flow channel can still be pushed back into the tundish chamber for maintenance without hitting the push rod 5 of the hydraulic drive assembly.

[0037] The plunger rod device for the flow channel system of a vacuum induction furnace of the present invention may further include a first electromagnetic directional valve 15, which has a first hydraulic interface and a second hydraulic interface. The hydraulic cylinder 1 includes an upper cylinder chamber 31, a piston 32, and a lower cylinder chamber 33. The upper cylinder chamber 31 has an upper hydraulic interface, and the lower cylinder chamber 33 has a lower hydraulic interface. The upper hydraulic interface of the upper cylinder chamber 31 is connected to the first hydraulic interface of the first electromagnetic directional valve 15 through an upper reciprocating air passage 16. The lower hydraulic interface of the lower cylinder chamber 33 is connected to the second hydraulic interface of the first electromagnetic directional valve 15 through a lower reciprocating air passage 17. The first electromagnetic directional valve 15 communicates with a hydraulic controller, which controls the movement direction of the hydraulic cylinder 1 by controlling the first electromagnetic directional valve 15.

[0038] As an optimization, the plunger rod device for the flow channel system of the vacuum induction furnace of the present invention may further include a bladder accumulator 18. The outlet of the bladder accumulator 18 is connected to the upper reciprocating air passage 16 and the lower reciprocating air passage 27 of the hydraulic cylinder 1 through a second electromagnetic directional valve 19. The outlet of the bladder accumulator 18 is flow-controlled by a throttle valve 20. The bladder accumulator 18 is switched on and off by a manual plate ball valve 22. The second electromagnetic directional valve 19 communicates with the hydraulic controller, and the hydraulic controller controls whether the bladder accumulator 18 is used for operation by controlling the second electromagnetic directional valve 19.

[0039] As an optimization, the plunger rod device for the flow channel system of a vacuum induction furnace of the present invention may further include a third electromagnetic directional valve 21. An upper proximity switch is provided in the upper cylinder chamber 31, and a lower proximity switch is provided in the lower cylinder chamber 33. The third electromagnetic directional valve 21 is connected to the upper reciprocating air path 16 and the lower reciprocating air path 17, respectively. The third electromagnetic directional valve 21 has a first control signal terminal corresponding to the interface of the upper reciprocating air path and a second control signal terminal corresponding to the interface of the lower reciprocating air path. The upper proximity switch, the lower proximity switch, the first control signal terminal, and the second control signal terminal all communicate with the hydraulic controller through signal terminals. The hydraulic controller controls the third electromagnetic directional valve 21 to switch the entire hydraulic drive assembly on and off. When the upper / lower proximity switch detects that the piston is in position, the upper / lower proximity switch feeds a feedback signal to the hydraulic controller, which then controls the third electromagnetic directional valve 21 to close, stopping the hydraulic drive assembly from retracting / pressing down.

[0040] The plunger rod device for the vacuum induction furnace flute system of the present invention not only improves the quality of production materials, but also increases the service life and stability of the mechanism. It makes the filtration and discharge of the pouring nozzle 14 of the flute C more controllable, and the superheat of the molten metal in the flute C is higher, so as to achieve lower production costs and higher material quality.

[0041] The plunger rod device for the flow channel system of a vacuum induction furnace of the present invention uses a hydraulic cylinder 1 to control the lifting and lowering of the plunger rod 13. Therefore, it has a high degree of automation, low labor intensity for workers, and low requirements for human factors, realizing humanized and simplified ergonomics, and is intuitive and easy to operate. At the same time, the entire hydraulic cylinder is located in a normal environment, ensuring the reliability of the equipment, making the equipment more operable, easy and simple to maintain, and low in operating costs.

[0042] In summary, the plunger rod device for the flow channel system of a vacuum induction furnace of the present invention improves the performance and automation level of the vacuum induction furnace, enhances the quality of vacuum-melted products, improves the material stability of vacuum-melted products, reduces the labor intensity of workers, expands continuous production efficiency, and achieves energy conservation, emission reduction, and green efficiency. It effectively solves the problems of incomplete nozzle sealing, high maintenance intensity, and short service life in traditional vacuum induction furnace flow channel systems.

[0043] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A plunger rod device for a flow channel system in a vacuum induction furnace, characterized in that, Includes a hydraulic drive assembly, a piston actuator, and a flow channel, wherein: The hydraulic drive assembly includes a hydraulic cylinder, a coupling, and a push rod. The hydraulic cylinder is fixed to the mounting flange on the top surface of the tundish of the flow channel via a sealing seat. The tundish of the flow channel is in a vacuum state. The hydraulic cylinder is located outside the tundish of the flow channel and is vacuum isolated from the tundish of the flow channel through the sealing seat. The extension rod of the hydraulic cylinder points downward, and the end of the extension rod of the hydraulic cylinder is connected to a push rod via a coupling. The plunger actuator includes a stop flange, a main support, a rocker arm, a transmission plate, a plunger rod, and two lever shafts. The main support is fixed to the side wall of the flow channel by a mounting bracket. The main support has vertically formed guide holes for the support column and two sets of guide holes for the lever shafts. The stop flange consists of a bearing flange and a support column connected to its bottom end. The support column is vertically movable and inserted into the guide holes of the support column. The stop flange is located directly below the push rod, and the push rod is coaxial with the support column. The two lever shafts... The rocker arm is inserted into the guide holes of the two sets of lever shafts, and each lever shaft moves up and down along the corresponding guide hole; the middle part of the rocker arm is rotatably set at the bottom end of the main support through a pin, and the rocker arm rotates and reciprocates around the pin; one end of the rocker arm is connected to the bottom end of the support column, and the other end is connected to the bottom end of the two lever shafts respectively; one end of the transmission plate is connected to the top end of the two lever shafts respectively, and the other end is connected to the top end of the plunger rod, and the plunger rod is aligned with the pouring nozzle of the flow channel.

2. The plunger rod device for a flow channel system in a vacuum induction furnace according to claim 1, characterized in that, The two lever shafts are arranged parallel to each other, and the bottom ends of the two lever shafts are connected to counterweights.

3. A plunger rod device for a flow channel system in a vacuum induction furnace according to claim 1, characterized in that, The bottom end of the plunger rod has a ceramic tip.

4. A plunger rod device for a flow channel system in a vacuum induction furnace according to claim 1, characterized in that, One end of the transmission plate is provided with a U-shaped groove, the top end of the plunger rod is set in the U-shaped groove and can be adjusted back and forth along the U-shaped groove, and the plunger rod and the pouring nozzle of the flow channel are kept coaxial.

5. A plunger rod device for a flow channel system in a vacuum induction furnace according to claim 1, characterized in that, A sealing ring is provided between the contact surface of the hydraulic cylinder and the sealing seat.

6. A plunger rod device for a flow channel system in a vacuum induction furnace according to claim 1, characterized in that, The load-bearing flange of the stop flange is made of graphite bronze.

7. A plunger rod device for a flow channel system in a vacuum induction furnace according to claim 1, characterized in that, During pouring, the hydraulic cylinder drives the push rod downward via the coupling, striking the bearing flange of the stop flange. The support column of the stop flange moves downward. During the downward movement of the support column, the rocker arm drives the two rod arms to move upward axially, which in turn drives the plunger rod upward via the transmission plate, moving it away from the pouring nozzle of the flow channel. When pouring stops, the hydraulic cylinder drives the push rod to retract via the coupling, stopping the pressure applied to the stop flange. The plunger actuator returns to its initial state, and the plunger rod moves downward under the action of gravity to block the pouring nozzle of the flow channel.

8. A plunger rod device for a flow channel system in a vacuum induction furnace according to claim 1, characterized in that, The hydraulic drive assembly further includes a first solenoid directional valve, which has a first hydraulic interface and a second hydraulic interface. The hydraulic cylinder includes an upper cylinder chamber, a piston, and a lower cylinder chamber. The upper cylinder chamber is provided with an upper hydraulic port, and the lower cylinder chamber is provided with a lower hydraulic port. The upper hydraulic port of the upper cylinder chamber is connected to the first hydraulic port of the first electromagnetic directional valve through the upper reciprocating air path; the lower hydraulic port of the lower cylinder chamber is connected to the second hydraulic port of the first electromagnetic directional valve through the lower reciprocating air path. The first electromagnetic directional valve communicates with the hydraulic controller, which controls the direction of movement of the hydraulic cylinder by controlling the first electromagnetic directional valve.

9. A plunger rod device for a flow channel system in a vacuum induction furnace according to claim 8, characterized in that, It also includes a bladder accumulator, the outlet of which is connected to the upper and lower reciprocating air circuits of the hydraulic cylinder via a second solenoid directional valve. The outlet of the bladder accumulator is flow-controlled via a throttle valve. The bladder accumulator is switched on and off via a manual plate ball valve. The second solenoid directional valve communicates with the hydraulic controller, which controls whether the bladder accumulator is used for operation by controlling the second solenoid directional valve.

10. A plunger rod device for a flow channel system in a vacuum induction furnace according to claim 8 or 9, characterized in that, It also includes a third electromagnetic directional valve. The upper cylinder chamber is equipped with an upper proximity switch, and the lower cylinder chamber is equipped with a lower proximity switch. The third electromagnetic directional valve is connected to the upper reciprocating air path and the lower reciprocating air path respectively. The third electromagnetic directional valve is equipped with a first control signal terminal corresponding to the upper reciprocating air path interface and a second control signal terminal corresponding to the lower reciprocating air path interface. The upper proximity switch, the lower proximity switch, the first control signal terminal, and the second control signal terminal all communicate with the hydraulic controller through signal terminals. The hydraulic controller controls the third electromagnetic directional valve to switch the entire hydraulic drive assembly on and off.

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