Clamp air cylinder control system with sudden stop and reverse thrust functions

Abstract

The invention discloses a clamp air cylinder control system with sudden stop and reverse thrust functions, which relates to the technical field of clamp air cylinder control systems and comprises an air source, a clamp air cylinder, a main control valve, a pneumatic clamping switch, a pneumatic opening switch and a clamp air cylinder sudden stop and reverse thrust control system. Comprising a PLC, an emergency stop reverse thrust control button electrically connected with the input end of the PLC, and a normally-open auxiliary control solenoid valve, a normally-closed on-off solenoid valve and a normally-open on-off solenoid valve which are electrically connected with the output end of the PLC. The normally-open auxiliary control electromagnetic valve is connected in the rodless cavity gas circuit in series, the normally-open on-off electromagnetic valve is connected in the rod cavity gas circuit in series, a reverse thrust control gas circuit is arranged between a rod cavity G opening of the clamp air cylinder and a gas source, and the normally-closed on-off electromagnetic valve is connected in the reverse thrust control gas circuit in series. Therefore, the emergency stop reverse thrust system is additionally arranged in an original clamp air cylinder, the rapid reverse thrust function is achieved, emergency stop of the clamp air cylinder is achieved, rapid reverse thrust is achieved, and therefore the safety of equipment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of clamp cylinder control systems, and in particular to a clamp cylinder control system with an emergency stop and reverse thrust function. Background Art

[0002] Pneumatic clamps are widely used in mechanical production. They respond quickly, and are easy to install, maintain, and operate. They can be used for large, medium, and small clamps. The principle of pneumatic clamps is relatively simple. They generally use the compressed air in the cylinder as a power source. By controlling the change in the air pressure in the cylinder, the pneumatic clamp can clamp or open the parts. In order to adapt to the development of large machinery, such as the clamp cylinders used in the production of large tractors, the size is also relatively large.

[0003] In the process of using pneumatic clamps to fix workpieces, it is inevitable to encounter emergencies, such as parts not being clamped in place, operators standing incorrectly, etc. If you encounter emergencies, you need to use the emergency stop switch to quickly shut down the air supply. Since the compressed air in the clamp cylinder has a huge thrust, even if the air supply is quickly shut off, there will still be a large residual air pressure in the pipeline, and it is difficult to quickly release the pressure through its own pressure relief port. Therefore, the remaining high-pressure air will push the piston rod of the clamp cylinder to continue moving. The entire pressure relief process will be very slow and cannot be stopped quickly, which will not only easily lead to the scrapping of parts, but also bring great safety hazards to operators. Summary of the invention

[0004] In order to overcome the above-mentioned defects, the purpose of the present invention is to provide a clamp cylinder control system with an emergency stop and reverse thrust function, which realizes a rapid reverse thrust function by adding an emergency stop and reverse thrust system to the original clamp cylinder, realizes the emergency stop of the clamp cylinder, and realizes rapid reverse thrust, thereby improving the safety of the equipment.

[0005] In order to achieve the above-mentioned objectives, the present invention provides a clamp cylinder control system with an emergency stop and reverse thrust function, including an air source and a clamp cylinder; a clamp cylinder normal working control system is provided between the air source and the clamp cylinder, and the clamp cylinder normal working control system is used to control the extension or retraction of the cylinder piston rod; the clamp cylinder normal working control system includes a main control valve, a pneumatic clamping switch, and a pneumatic opening switch; the main control valve is connected to the air source through a main air circuit, the main control valve working port A is connected to the rod cavity G port of the clamp cylinder through a rod cavity air circuit, and the main control valve working port B is connected to the rodless cavity H port of the clamp cylinder through a rodless cavity air circuit; the pneumatic clamping switch is connected to the air source through a main air circuit. The automatic opening switch is connected in parallel and is connected with the main air circuit; it is characterized in that it also includes: a clamp cylinder emergency stop and reverse thrust control system, the clamp cylinder emergency stop and reverse thrust control system includes: a PLC controller, an emergency stop and reverse thrust control button electrically connected to the input end of the PLC controller, a normally open auxiliary control solenoid valve, a normally closed on-off solenoid valve and a normally open on-off solenoid valve electrically connected to the output end of the PLC controller respectively; the normally open auxiliary control solenoid valve is connected in series in the rodless cavity air circuit, the normally open on-off solenoid valve is connected in series in the rod cavity air circuit, a reverse thrust control air circuit is arranged between the G port of the rod cavity of the clamp cylinder and the air source, and the normally closed on-off solenoid valve is connected in series in the reverse thrust control air circuit.

[0006] Preferably, the main control valve is a two-position five-way valve, and the normally open auxiliary control solenoid valve is a two-position two-way solenoid valve, and the two-position two-way solenoid valve is provided with an air release port R.

[0007] Preferably, the PLC controller is electrically connected to a time relay, and the PLC controller and the time relay are both located in an electric control box and are electrically connected to a power module respectively.

[0008] Preferably, the time relay is a delayed time relay, and the reverse thrust control air circuit is connected to the rod cavity air circuit via a three-way air circuit joint.

[0009] Preferably, the PLC controller is electrically connected to a plurality of the emergency stop and reverse thrust control buttons, and the plurality of the emergency stop and reverse thrust control buttons are connected in parallel.

[0010] Preferably, the clamp cylinder control system also includes an air circuit valve row, and a plurality of the clamp cylinders are arranged in parallel, and the main control valve corresponding to each of the clamp cylinders is connected to the air circuit valve row, and the air circuit valve row is connected to the air source through the main air circuit.

[0011] Preferably, a control method for a clamp cylinder control system with an emergency stop and reverse thrust function comprises the following steps:

[0012] Normal clamping: When the workpiece needs to be clamped, the pneumatic clamping switch is operated, and the compressed air of the air source passes through the main air circuit, the main control valve working port B, the rodless cavity air circuit, and the normally open auxiliary control solenoid valve, and enters the rodless cavity of the clamp cylinder, and the cylinder piston rod extends to clamp the workpiece;

[0013] Normal release: When the workpiece needs to be removed, the pneumatic opening switch is operated, and the compressed air of the air source enters the rod cavity of the clamp cylinder through the main air circuit, the main control valve working port A, the rod cavity air circuit, and the normally open on-off solenoid valve, and the cylinder piston rod contracts to release the workpiece;

[0014] Emergency stop and reverse thrust: In case of an emergency, press the emergency stop and reverse thrust control button, the PLC controller controls the normally open auxiliary control solenoid valve to connect the right phase, the normally closed on-off solenoid valve opens, and the normally open on-off solenoid valve closes, and the compressed air from the air source passes through the main air circuit, the reverse thrust control air circuit, and the normally closed on-off solenoid valve, and enters the rod chamber of the clamp cylinder, and the cylinder piston rod quickly contracts and resets.

[0015] Preferably, the normally open auxiliary control solenoid valve adopts a two-position two-way solenoid valve, and the two-position two-way solenoid valve is provided with an air vent R; in the emergency stop reverse thrust step, when the cylinder piston rod contracts, the compressed air in the rodless cavity of the clamp cylinder is depressurized through the rodless cavity air circuit and the air vent R of the normally open auxiliary control solenoid valve.

[0016] Preferably, the PLC controller is electrically connected to a time relay, and the time relay is a delayed time relay; in the emergency stop and reverse thrust step, the PLC controller first controls the normally open auxiliary control solenoid valve, so that the rodless chamber of the clamp cylinder is connected to the air vent R of the normally open auxiliary control solenoid valve, and then controls the normally closed on-off solenoid valve to open, and the normally open on-off solenoid valve to close.

[0017] After adopting the above technical solution, the beneficial technical effects achieved by the present invention are:

[0018] 1. Since the clamp cylinder emergency stop reverse thrust control system is added to the normal working control system of the clamp cylinder, the system includes a PLC controller, an emergency stop reverse thrust control button electrically connected to the input end of the PLC controller, a normally open auxiliary control solenoid valve, a normally closed on-off solenoid valve and a normally open on-off solenoid valve electrically connected to the output end of the PLC controller respectively; the normally open auxiliary control solenoid valve is connected in series in the rodless cavity air circuit, the normally open on-off solenoid valve is connected in series in the rod cavity air circuit, a reverse thrust control air circuit is provided between the G port of the rod cavity of the clamp cylinder and the air source, and the normally closed on-off solenoid valve is connected in series in the reverse thrust control air circuit. When the clamp cylinder encounters an unexpected abnormal situation during the clamping process, the emergency stop reverse thrust control button is used to close the original air intake valve in time, and the rodless cavity of the clamp cylinder is quickly connected to the pressure relief port R to achieve rapid pressure relief, and the rod cavity air circuit of the clamp cylinder is quickly inlet, and the piston rod of the clamp cylinder is reversely retracted, which can avoid the expansion of losses.

[0019] 2. Due to the setting of the normally open auxiliary control solenoid valve, after receiving the electrical signal from the PLC controller, it can quickly switch to connect the rodless cavity H port of the fixture cylinder with the air relief port R to achieve rapid pressure relief, and synchronously cooperate with the reverse thrust control air circuit. The thrust of the rod cavity of the fixture cylinder can effectively realize the timely stop and retraction of the cylinder piston rod, solving the problem that the cylinder used in pneumatic chemical equipment and pneumatic fixtures cannot be stopped quickly and effectively in time. In particular, it can avoid the industry drawbacks of workpiece extrusion and deformation caused by sudden abnormalities and the safety of operators, ensuring the operating safety of operators.

[0020] 3. Due to the setting of the gas circuit valve row, multiple fixture cylinders can be connected in parallel and controlled by the same set of fixture cylinder emergency stop and reverse thrust control system. In actual use, according to the actual working conditions, several emergency stop and reverse thrust control buttons can be connected in parallel, which will respond more quickly to emergencies and improve the safety factor.

[0021] 4. On the basis of the normal working control system of the fixture cylinder, several gas circuits are set up, and the normally open auxiliary control solenoid valve, the normally closed on-off solenoid valve and the normally open on-off solenoid valve are connected in series in the gas circuits that need to be controlled. The installation method is simple and suitable for the modification of the existing normal fixture cylinder. The cost is extremely low and the practicability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a control principle diagram of the clamp cylinder in the air circuit emergency stop reverse thrust system of the pneumatic clamp of the present invention being in a clamping state;

[0023] Figure 2 It is a control principle diagram of the clamp cylinder of the present invention in an emergency stop reverse thrust state;

[0024] In the figure,

[0025] 1. Clamp cylinder; 2. Air source; 3. Air circuit valve row; 4. Pneumatic clamping switch; 5. Pneumatic opening switch; 6. PLC controller; 7. Time relay; 8. Power module; 9. Emergency stop reverse push control button; 10. Main control valve; 11. Normally open auxiliary control solenoid valve; 12. Normally open on-off solenoid valve; 13. Normally closed on-off solenoid valve; 14. Air circuit three-way connector;

[0026] L1, main air circuit; L2, rodless cavity air circuit; L3, rod cavity air circuit; L4, reverse thrust control air circuit. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] See also Figure 1 , Figure 2 The dotted line part in the figure is the electric control line.

[0029] The present invention provides a clamp cylinder control system with an emergency stop and reverse thrust function, the clamp cylinder control system comprises: an air source 2 and a clamp cylinder 1; a clamp cylinder normal working control system is arranged between the air source 2 and the clamp cylinder 1, the clamp cylinder normal working control system is used to control the extension or retraction of the cylinder piston rod; the clamp cylinder normal working control system comprises a main control valve 10, a pneumatic clamping switch 4, and a pneumatic opening switch 5; the main control valve 10 is connected to the air source 2 through a main air circuit L1, the working port A of the main control valve 10 is connected to the rod cavity G port of the clamp cylinder 1 through a rod cavity air circuit L3, and the working port B of the main control valve 10 is connected to the rodless cavity H port of the clamp cylinder 1 through a rodless cavity air circuit L2; the pneumatic clamping switch 4 is connected in parallel with the pneumatic opening switch 5, and is connected to the main air circuit L1. The above is the normal working state of the clamp cylinder 1, including conventional actions such as clamping and opening of the workpiece. The control method of the above clamp cylinder 1 is a mature existing technology, which can be controlled manually or connected to a control system to achieve automatic operation. It is a mature existing technology and will not be described in detail.

[0030] On the basis of the normal working control system of the clamp cylinder, an emergency stop and reverse thrust control system of the clamp cylinder is added. The clamp cylinder emergency stop and reverse thrust control system includes: a PLC controller 6, an emergency stop and reverse thrust control button 9 electrically connected to the input end of the PLC controller 6, a normally open auxiliary control solenoid valve 11, a normally closed on-off solenoid valve 13 and a normally open on-off solenoid valve 12 electrically connected to the output end of the PLC controller 6 respectively; the normally open auxiliary control solenoid valve 11 is connected in series in the rodless cavity air circuit L2, the normally open on-off solenoid valve 12 is connected in series in the rod cavity air circuit L3, a reverse thrust control air circuit is provided between the G port of the rod cavity of the clamp cylinder 1 and the air source 2, and the normally closed on-off solenoid valve 13 is connected in series in the reverse thrust control air circuit. The clamp cylinder emergency stop and reverse thrust control system mainly includes two actions, emergency stop and reverse thrust. Emergency stop and reverse thrust are only required when the clamp cylinder 1 is in a normal clamping state. Emergency stop is not required when the clamp cylinder 1 is normally opened or normally closed. When encountering an emergency, manually press any emergency stop reverse thrust control button 9, the PLC controller 6 receives the signal, the normally open auxiliary control solenoid valve 11 receives the signal, and quickly switches to the right phase. At this time, the K port and the R port are connected, and the K port and the P port are cut off. At this time, the high-pressure air in the rodless cavity of the clamp cylinder 1 is connected to the R port to achieve rapid pressure relief. The above steps are to quickly discharge the residual high-pressure gas in the clamp cylinder 1 and each high-pressure pipeline. The normally open on-off solenoid valve 12 is closed after being energized, and the normally closed on-off solenoid valve 13 is opened after being energized. At this time, the reverse thrust control air circuit L4 is connected to the rod cavity of the clamp cylinder 1 to realize the reverse thrust function. In the above process, the direct switching of the solenoid valve is generally performed directly, and the response is extremely rapid. At the same time, there is always high-pressure air in the rod cavity air circuit L3 and the reverse thrust control air circuit L4, and after the state conversion, thrust can be directly provided.

[0031] The PLC controller 6 and the time relay 7 are both located in the electric control box and are electrically connected to the power module 8. The power module 8 provides power for each electronic device in the electric control box, and generally adopts a DC24V power supply.

[0032] The main control valve 10 of the present invention adopts a two-position five-way valve, and the normally open auxiliary control solenoid valve 11 adopts a two-position two-way solenoid valve, and the two-position two-way solenoid valve is provided with an air release port R. Since the power of the clamp cylinder 1 comes from the high-pressure air provided by the air source 2, it is necessary to quickly release the pressure through the air release port R while cutting off the air inlet end before realizing the reverse thrust operation. Therefore, the time relay 7 is electrically connected to the PLC controller 6, and the time relay 7 is generally a delayed time relay to ensure that the pressure is released first and then the reverse thrust function is realized to prevent excessive pressure from damaging the air circuit. The reverse thrust control air circuit L4 is connected to the rod cavity air circuit L3 through the air circuit three-way joint 14.

[0033] The PLC controller 6 of the present invention is electrically connected with a plurality of emergency stop reverse thrust control buttons 9, and the plurality of emergency stop reverse thrust control buttons 9 are connected in parallel. The emergency stop reverse thrust control buttons 9 are all connected in parallel, and a plurality of them can be set according to the actual position requirements to ensure that the safety of the operation can be guaranteed to the maximum extent. In order to ensure the effectiveness of the reverse thrust control gas circuit 14, the gas circuit three-way connector 14 must be located at the D port of the normally open on-off solenoid valve 12 and the front end of the normally closed on-off solenoid valve 13.

[0034] The clamp cylinder control system of the present invention further includes an air circuit valve row 3, and a plurality of clamp cylinders 1 are arranged in parallel, and the main control valve 10 corresponding to each clamp cylinder 1 is connected to the air circuit valve row 3, and the air circuit valve row 3 is connected to the gas source 2 through the main gas circuit L1. The air circuit valve row 3 is used to divide the high-pressure gas provided by the gas source 2 into a plurality of branches, and in actual operation, it generally controls a plurality of clamp cylinders 1 to work together.

[0035] A control method for a clamp cylinder control system with an emergency stop and reverse thrust function comprises the following steps:

[0036] See also Figure 1 Normal clamping: When the workpiece needs to be clamped, the pneumatic clamping switch 4 is operated, and the compressed air of the air source 2 enters the rodless cavity of the clamp cylinder 1 through the main air circuit L1, the working port B of the main control valve 10, the rodless cavity air circuit L2, and the normally open auxiliary control solenoid valve 11. The cylinder piston rod extends to clamp the workpiece. Normal loosening: When the workpiece needs to be removed, the pneumatic opening switch 5 is operated, and the compressed air of the air source 2 enters the rod cavity of the clamp cylinder 1 through the main air circuit L1, the working port A of the main control valve 10, the rod cavity air circuit L3, and the normally open on-off solenoid valve 12. The cylinder piston rod contracts and the workpiece is loosened. The above-mentioned normal clamping and normal opening are the normal working states of the clamp cylinder 1, which mainly rely on the main control valve 10 to realize the switching of the air circuit, and other solenoid valves do not need to be operated.

[0037] See also Figure 2 , Emergency stop reverse thrust: In case of an emergency, press the emergency stop reverse thrust control button 9, the PLC controller 6 controls the normally open auxiliary control solenoid valve 11 to connect the right phase, the normally closed on-off solenoid valve 13 opens, and the normally open on-off solenoid valve 12 closes. The compressed air of the air source 2 enters the rod chamber of the clamp cylinder 1 through the main air circuit L1, the reverse thrust control air circuit L4, and the normally closed on-off solenoid valve 13, and the piston rod of the cylinder quickly contracts and resets. The normally open auxiliary control solenoid valve 11 of the present invention adopts a two-position two-way solenoid valve, and the two-position two-way solenoid valve is provided with an air release port R; in the emergency stop reverse thrust step, when the cylinder piston rod contracts, the compressed air in the rodless chamber of the clamp cylinder 1 is depressurized through the rodless chamber air circuit L2 and the air release port R of the normally open auxiliary control solenoid valve 11. The two-position two-way solenoid valve can be purchased directly according to the model.

[0038] The PLC controller 6 is electrically connected with a time relay 7, which is a time delay relay; in the emergency stop reverse push step, the PLC controller 6 first controls the normally open auxiliary control solenoid valve 11, so that the rodless chamber of the clamp cylinder 1 is connected to the air release port R of the normally open auxiliary control solenoid valve 11, and then controls the normally closed on-off solenoid valve 13 to open, and the normally open on-off solenoid valve 12 to close. According to the response time of each solenoid valve, the delay time of the time relay 7 is generally 0.1-2S, and the shorter the time, the better, to ensure that the pressure is released first, and then reverse push, mainly to ensure that the corresponding solenoid valve is completely opened, and can also be used to ensure the safety of the gas circuit. In actual use, a virtual time relay can also be directly set in the PLC controller 6 for the delay function. This method is software controlled, which is the same as the role of the time relay 7 in this application. One of the two can be selected.

[0039] In actual use, if the clamp cylinder 1 of the present invention is applied to the movement of a slide-type base, the positions of the air inlet and air outlet of the clamp cylinder 1 can be switched, and the emergency stop and reverse thrust function can also be realized during the opening process of the clamp cylinder 1. The above embodiment has a relatively low frequency of use.

[0040] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A clamp cylinder control system with an emergency stop and reverse thrust function, the clamp cylinder control system comprising: An air source and a clamp cylinder; a clamp cylinder normal working control system is provided between the air source and the clamp cylinder, and the clamp cylinder normal working control system is used to control the extension or retraction of the cylinder piston rod; the clamp cylinder normal working control system includes a main control valve, a pneumatic clamping switch, and a pneumatic opening switch; the main control valve is connected to the air source through a main air circuit, the main control valve working port A is connected to the rod cavity G port of the clamp cylinder through a rod cavity air circuit, and the main control valve working port B is connected to the rodless cavity H port of the clamp cylinder through a rodless cavity air circuit; the pneumatic clamping switch is connected in parallel with the pneumatic opening switch and is connected to the main air circuit; it is characterized in that it also includes: A clamp cylinder emergency stop and reverse thrust control system, the clamp cylinder emergency stop and reverse thrust control system comprises: a PLC controller, an emergency stop and reverse thrust control button electrically connected to the input end of the PLC controller, a normally open auxiliary control solenoid valve, a normally closed on-off solenoid valve and a normally open on-off solenoid valve electrically connected to the output end of the PLC controller respectively; the normally open auxiliary control solenoid valve is connected in series in the rodless cavity air circuit, the normally open on-off solenoid valve is connected in series in the rod cavity air circuit, a reverse thrust control air circuit is arranged between the G port of the rod cavity of the clamp cylinder and the air source, and the normally closed on-off solenoid valve is connected in series in the reverse thrust control air circuit.

2. The clamp cylinder control system with emergency stop and reverse thrust function according to claim 1, characterized in that: The main control valve adopts a two-position five-way valve, and the normally open auxiliary control solenoid valve adopts a two-position two-way solenoid valve. The two-position two-way solenoid valve is provided with an air release port R.

3. The clamp cylinder control system with emergency stop and reverse thrust function according to claim 1, characterized in that: The PLC controller is electrically connected to a time relay. The PLC controller and the time relay are both located in an electric control box and are electrically connected to a power supply module respectively.

4. The clamp cylinder control system with emergency stop and reverse thrust function according to claim 3, characterized in that: The time relay is a time-delay time relay, and the reverse thrust control air circuit is connected with the rod cavity air circuit via an air circuit three-way joint.

5. The clamp cylinder control system with emergency stop and reverse thrust function according to claim 1, characterized in that: The PLC controller is electrically connected to a plurality of the emergency stop and reverse thrust control buttons, and the plurality of the emergency stop and reverse thrust control buttons are connected in parallel.

6. The clamp cylinder control system with emergency stop and reverse thrust function according to claim 1, characterized in that: The clamp cylinder control system also includes an air circuit valve row, and the clamp cylinders are provided with multiple valves in parallel. The main control valve corresponding to each of the clamp cylinders is connected to the air circuit valve row, and the air circuit valve row is connected to the air source through the main air circuit.

7. The control method of the clamp cylinder control system with emergency stop and reverse thrust function according to claim 1, characterized in that: The control method comprises the following steps: Normal clamping: When the workpiece needs to be clamped, the pneumatic clamping switch is operated, and the compressed air of the air source passes through the main air circuit, the main control valve working port B, the rodless cavity air circuit, and the normally open auxiliary control solenoid valve, and enters the rodless cavity of the clamp cylinder, and the cylinder piston rod extends to clamp the workpiece; Normal release: When the workpiece needs to be removed, the pneumatic opening switch is operated, and the compressed air of the air source enters the rod cavity of the clamp cylinder through the main air circuit, the main control valve working port A, the rod cavity air circuit, and the normally open on-off solenoid valve, and the cylinder piston rod contracts to release the workpiece; Emergency stop and reverse thrust: In case of an emergency, press the emergency stop and reverse thrust control button, the PLC controller controls the normally open auxiliary control solenoid valve to connect the right phase, the normally closed on-off solenoid valve opens, and the normally open on-off solenoid valve closes. The compressed air from the air source passes through the main air circuit, the reverse thrust control air circuit, and the normally closed on-off solenoid valve, and enters the rod chamber of the clamp cylinder, and the cylinder piston rod quickly contracts and resets.

8. The control method of the clamp cylinder control system with emergency stop reverse thrust function according to claim 7, characterized in that: The normally open auxiliary control solenoid valve adopts a two-position two-way solenoid valve, and the two-position two-way solenoid valve is provided with an air vent R; in the emergency stop reverse thrust step, when the cylinder piston rod contracts, the compressed air in the rodless cavity of the clamp cylinder is depressurized through the rodless cavity air circuit and the air vent R of the normally open auxiliary control solenoid valve.

9. The control method of the clamp cylinder control system with emergency stop reverse thrust function according to claim 8, characterized in that: The PLC controller is electrically connected to a time relay, which is a delayed time relay; in the emergency stop and reverse thrust step, the PLC controller first controls the normally open auxiliary control solenoid valve, so that the rodless chamber of the clamp cylinder is connected to the air vent R of the normally open auxiliary control solenoid valve, and then controls the normally closed on-off solenoid valve to open, and the normally open on-off solenoid valve to close.

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