CN213981403U

CN213981403U - Automatic control system for pipeline groove

Info

Publication number: CN213981403U
Application number: CN202022209035.XU
Authority: CN
Inventors: 邹建强; 孙景林; 刘洋; 刘百冰
Original assignee: Guodian Electric Power Development Co Ltd And Yu Hydropower Development Co ltd
Current assignee: Guodian Electric Power Development Co Ltd And Yu Hydropower Development Co ltd
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2021-08-17
Anticipated expiration: 2030-09-30

Abstract

The utility model provides an automatic control system for pipeline groove, belongs to full automatic cutout technical field, including hydraulic pump start from reset button, hydraulic pump stop from reset button, mode switch handle, have overvoltage overcurrent and earth leakage protection's three-phase 3P circuit breaker, inductance type proximity switch and PLC controller etc. three-phase 3P circuit breaker with overvoltage overcurrent and earth leakage protection links to each other with three-phase AC inlet wire main power supply and the three-phase 3P circuit breaker with overcurrent protection, three-phase 3P circuit breaker with overcurrent protection links to each other with hydraulic pump start contactor, and running indicator lamp, fault indicator lamp, warning buzzer, cutter rise and decline auxiliary relay coil link to each other with PLC controller switching value output module. The system can complete pipeline cutting and groove work in a full-automatic and high-efficiency mode by matching with a hydraulic station and a corresponding mechanical part, simplifies loop wiring, reduces the number of contacts, has an electrical protection function, and effectively protects automatic components, hydraulic station facilities and the like from being damaged.

Description

Automatic control system for pipeline groove

Technical Field

The utility model belongs to the technical field of full-automatic cutting, concretely relates to automatic control system for pipeline groove.

Background

The pipeline beveling machine is a special tool for chamfering the front end face of the pipeline before welding, effectively solves the problems of irregular operation processes such as polishing and polishing, flame cutting and the like, rough slope, low working efficiency, high working noise and the like, and has the advantages of simple and convenient operation, standard angle, smooth cutting surface and the like. However, most of the existing automatic control systems of the beveling machine are control systems consisting of pure relays and contactors, the wiring quantity is large, and the wiring is complicated, so that when a fault occurs, a large amount of labor and time are needed to remove the fault; meanwhile, the existing beveling machine control system lacks necessary electrical protection functions like automatic stop after overtime operation and the like, so that the damage of electrical components and the overheating and aging conditions of a hydraulic station motor are easily caused, and a large amount of component purchase cost is wasted; in addition, current automatic control system lacks some humanized functions, and operation flow is troublesome relatively, and efficiency is not high, for example step on the footboard, the function of groove work is once accomplished in the cutter just can full stroke work, or the cutter can break away from the work position automatically under certain operating mode, makes things convenient for operating personnel to carry out the function of clearing up to the butt cinder, again or when the machine breaks down unusually, reminds operating personnel's function etc. through the dual warning of pilot lamp and bee calling organ.

SUMMERY OF THE UTILITY MODEL

Based on the technical problem, the utility model provides a novel automatic control system for pipeline groove, this system greatly simplify the return circuit wiring, reduce contact quantity, have comprehensive electrical protection function, effectively protect automatic components and parts and hydraulic pressure station facility etc. not damaged.

The utility model adopts the following technical scheme:

an automatic control system for a pipeline groove comprises a hydraulic pump starting self-reset button, a hydraulic pump stopping self-reset button, a mode switching handle, a three-phase 3P circuit breaker with overvoltage, overcurrent and electric leakage protection, a three-phase 3P circuit breaker with overcurrent protection, a single-phase 2P circuit breaker with overcurrent protection, a PLC controller, a hydraulic pump starting contactor, a cutter lifting intermediate relay, a cutter descending intermediate relay, a cutter lifting electromagnetic valve, a cutter descending electromagnetic valve and a thermal element with overcurrent fixed value adjustment, wherein the three-phase 3P circuit breaker with overvoltage, overcurrent and electric leakage protection is connected with a three-phase alternating current inlet wire main power supply and the three-phase 3P circuit breaker with overcurrent protection, the three-phase 3P circuit breaker with overcurrent protection is connected with the hydraulic pump starting contactor, the hydraulic pump starting contactor is connected with the thermal element with overcurrent fixed value adjustment, the thermal element with the overcurrent constant value regulation is connected with a hydraulic pump motor, the output lower end of the three-phase 3P circuit breaker with overvoltage, overcurrent and leakage protection is connected with an alternating current 220V control power supply and a single-phase 2P circuit breaker with overcurrent protection, the single-phase 2P circuit breaker with overcurrent protection is connected with a PLC (programmable logic controller), the single-phase 2P circuit breaker with overcurrent protection is connected with a hydraulic pump starting self-reset button, the hydraulic pump starting self-reset button is connected with a hydraulic pump stopping self-reset button, the hydraulic pump stopping self-reset button is connected with a hydraulic pump starting contactor coil, the hydraulic pump starting contactor coil is connected with a thermal element auxiliary contact with the overcurrent constant value regulation, the thermal element auxiliary contact with the overcurrent constant value regulation is connected with the output zero line end of the single-phase 2P circuit breaker with overcurrent protection to form a loop, and the PLC is connected with a cutter lifting middle relay coil, The utility model discloses a cutter descending relay, including cutter ascending solenoid valve, cutter descending solenoid valve coil, single-phase 2P circuit breaker output live wire end that has overcurrent protection links to each other with the one end of cutter ascending relay, the auxiliary contact of cutter descending relay, the other end of cutter ascending relay, the auxiliary contact of cutter descending relay links to each other with cutter ascending solenoid valve, cutter descending solenoid valve coil one end, and cutter ascending solenoid valve, the other end of cutter descending solenoid valve coil all link to each other with the single-phase 2P circuit breaker output live wire end that has overcurrent protection and constitute the return circuit.

Furthermore, the system also comprises a deslagging position inductive proximity switch, an upper limit position inductive proximity switch, a middle position inductive proximity switch, a lower limit position inductive proximity switch and a pedal self-reset switch, wherein the signal output ends of the deslagging position inductive proximity switch, the upper limit position inductive proximity switch, the middle position inductive proximity switch and the lower limit position inductive proximity switch are respectively connected with the switching value input end of the PLC controller, the input power ends of the deslagging position inductive proximity switch, the upper limit position inductive proximity switch, the middle position inductive proximity switch and the lower limit position inductive proximity switch are respectively connected with the switching value input end of the PLC controller, the anode of the self-produced 24V power supply of the PLC controller is connected with one end of a mode switching handle contact, the other end of the mode switching handle contact is connected with the switching value input end of the PLC controller, the positive electrode of a 24V power supply self-generated by the PLC is connected with one end of a pedal self-reset switch contact, and the other end of the pedal self-reset switch contact is connected with the switching value input end of the PLC.

Furthermore, the system also comprises an operation indicator light, a fault indicator light and an alarm buzzer, wherein the operation indicator light, the fault indicator light and the alarm buzzer are connected with the switching value output end of the PLC.

Furthermore, the output lower end of the three-phase 3P circuit breaker with overvoltage, overcurrent and leakage protection is connected with a single-phase 2P circuit breaker with overcurrent protection, and a single-phase power supply and a zero line form an alternating current 220V control power supply.

The utility model discloses an advantage and effect do:

1. effectively ensure the safe and stable operation of the equipment.

2. The electric protection function of the equipment is added, and the safety of personnel and the equipment is effectively guaranteed.

3. The operation is simple and easy to operate, the manual operation cost is practically reduced, and the working efficiency of the pipeline groove is effectively improved.

4. The PLC is used as a control core, so that the complexity of a control loop is greatly simplified, the failure rate of equipment is effectively reduced, and a large amount of maintenance cost is saved.

5. The functions of power-on initialization of the cutting equipment and convenience for operating personnel to process the cutting slag are added, the cutting slag is convenient to clean, and the operation requirements of the cutting equipment under various working conditions are met.

Drawings

FIG. 1 is a logic flow diagram of an automatic control system for a pipe groove;

FIG. 2 is a schematic wiring diagram of an automatic control system for a pipe groove;

fig. 3 is a ladder diagram of the program of the automatic control system of the pipeline groove.

Fig. 4 is a PLC point gauge of the automatic control system of the pipeline groove.

In the figure: 1. an operation indicator lamp, 2 a fault indicator lamp, 3 an alarm buzzer, 4 a hydraulic pump starting self-reset button, 5 a hydraulic pump stopping self-reset button, 6 a mode switching handle, 7 a three-phase 3P circuit breaker with overvoltage, overcurrent and leakage protection, 8 a three-phase 3P circuit breaker with overcurrent protection, 9 a single-phase 2P circuit breaker with overcurrent protection, 10 a PLC controller, 11 a hydraulic pump starting contactor, 12. a cutter lifting intermediate relay, 13, a cutter descending intermediate relay, 14, a deslagging position inductive proximity switch, 15, an upper limit inductive proximity switch, 16, an intermediate position inductive proximity switch, 17, a lower limit inductive proximity switch, 18, a pedal self-reset switch, 19, a cutter lifting electromagnetic valve, 20, a cutter descending electromagnetic valve and 21, and a thermal element with an overcurrent fixed value adjustment function.

Detailed Description

The present invention will be further explained with reference to the drawings and examples.

As shown in fig. 1-4, the utility model relates to a novel automatic control system for pipeline groove includes: three-phase 3P circuit breaker (incoming line main power supply) with overvoltage and overcurrent protection, three-phase 3P circuit breaker (hydraulic pump power supply) with overcurrent protection, single-phase 2P circuit breaker (control loop power supply) with overcurrent protection, hydraulic pump motor thermal element capable of adjusting overcurrent fixed value, programmable logic PLC controller, inductive proximity switch (upper limit), inductive proximity switch (middle position), inductive proximity switch (lower limit), inductive proximity switch (slag removal position), hydraulic pump starting self-reset button, hydraulic pump stopping self-reset button, pedal self-reset switch, mode switching handle (normal working mode/cutter lifting slag removal mode), hydraulic pump starting contactor, cutter lifting intermediate relay, cutter lowering intermediate relay, operation indicator lamp, fault indicator lamp, alarm buzzer, cutter lifting electromagnetic valve, power supply, and control system, The cutter descends the solenoid valve.

Three-phase 3P circuit breaker (inlet wire total power) with excessive pressure overflows and earth leakage protection, the effect prevents that total power input end voltage is unusual to produce the influence to control system, uses as hydraulic pump and control loop switch's back-up protection simultaneously, in addition, can also effectively avoid bringing the safety risk for operation and maintainer because of the equipment electric leakage.

The three-phase 3P circuit breaker (hydraulic pump power supply) with overcurrent protection has the function of quickly disconnecting the power supply when the three-phase winding of the hydraulic pump motor is in insulation reduction, short circuit or grounding, so that the influence range is reduced while the motor is protected.

The single-phase 2P circuit breaker (control circuit power supply) with overcurrent protection has the function that when the control circuit is in an abnormal state such as short circuit or grounding, the power supply can be quickly cut off, automatic components are protected, and the influence range is reduced.

The hydraulic pump motor thermal element with the adjustable overcurrent fixed value has the function that when the motor winding is in overcurrent, a power supply can be quickly cut off to protect the motor, and the thermal element with the adjustable value can be adapted to motors of various models.

The PLC is the core of the whole set of automatic control system, and the acquisition of each state quantity information and the issuing of various instructions are realized by compiling programs.

The inductance type approach switch (upper limit) is the highest position of the cutter in normal operation, namely the upper limit of the cutter.

The inductive proximity switch (middle position) is the middle position of the cutter in normal operation, namely the position of the cutter for power-on initialization.

The inductance type proximity switch (lower limit) is the lowest position of the cutter in normal operation, namely the lower limit of the cutter.

The inductive proximity switch (deslagging position) is a position for lifting the cutter to deslag.

The hydraulic pump is started by the self-reset button and is used for starting the hydraulic pump to start working.

The hydraulic pump stops the self-reset button and has the function of stopping the hydraulic pump.

The pedal is a self-reset switch, namely under the normal working condition of the hydraulic station, the cutter is in the middle position, and when the pedal is stepped, the groove cutter can automatically run for one time in the full stroke (middle limit, lower limit, middle limit, upper limit and middle limit).

The mode switching handle (a normal working mode/a cutter lifting deslagging mode) is used for switching between the two modes, and when the mode is switched to the cutter lifting deslagging mode, the cutter can be automatically lifted to a deslagging position no matter at any position; when the cutter is switched to a normal working mode, the cutter automatically returns to the middle limiting position.

The hydraulic pump starts the contactor, and the function is to automatically send the three-phase power supply to the hydraulic pump motor to enable the hydraulic pump motor to operate.

The cutter ascending intermediate relay is used for converting an output instruction of the cutter ascending of the programmable PLC controller to a cutter ascending electromagnetic valve, and aims to prevent PLC contacts from being burnt when a coil of the electromagnetic valve descends in an insulation mode or is in a short circuit mode.

The cutter descending intermediate relay is used for converting an output instruction of cutter descending of the programmable PLC controller to the cutter descending electromagnetic valve, and aims to prevent PLC contacts from being burnt when a coil of the electromagnetic valve descends in an insulating mode or is in a short circuit mode.

The operation indicator lamp is lighted when the hydraulic pump is operated.

The fault indicator lamp is turned on when faults such as overcurrent, overvoltage, cutter power-on initialization failure, cutter blockage, long-time electrification of the electromagnetic valve and the like occur in the system.

The alarm buzzer is consistent with the lighting action condition of the fault lamp, and when the system is in fault, the buzzer sounds for 20 seconds.

The cutter lifting electromagnetic valve is an element for executing cutter lifting and oil pressure conveying.

The cutter descending electromagnetic valve is an element for executing cutter descending and oil pressure conveying.

The three-phase AC incoming line main power supply is connected with the input upper end of a three-phase 3P circuit breaker 7 with overvoltage, overcurrent and electric leakage protection, the output lower end of the three-phase 3P circuit breaker 7 with overvoltage, overcurrent and electric leakage protection is connected with the input upper end of a three-phase 3P circuit breaker 8 with overcurrent protection, the output lower end of the three-phase 3P circuit breaker 8 with overcurrent protection is connected with the input upper end of a hydraulic pump starting contactor 11, the output lower end of the hydraulic pump starting contactor 11 is connected with the input upper end of a thermal element 21 with overcurrent constant value regulation, the output lower end of the thermal element 21 with overcurrent constant value regulation is directly connected with a hydraulic pump motor, an AC 220V control power supply consisting of a single-phase power supply and a zero line is taken from the output lower end of the three-phase 3P circuit breaker 7 with overvoltage, overcurrent and electric leakage protection and is connected with the input upper end of a single-phase 2P circuit breaker 9 with overcurrent protection, the output lower end of the single-phase 2P circuit breaker 9 with overcurrent protection is connected with the input power supply end of a programmable logic PLC controller 10, the output live wire end of a single-phase 2P circuit breaker 9 with overcurrent protection is connected with one end of a normally open contact of a hydraulic pump starting self-reset button 4, the other end of the normally open contact of the hydraulic pump starting self-reset button 4 is connected with one end of a normally closed contact of a hydraulic pump stopping self-reset button 5, the other end of the normally closed contact of the hydraulic pump stopping self-reset button 5 is connected with one end of a coil of a hydraulic pump starting contactor 11, the other end of the coil of the hydraulic pump starting contactor 11 is connected with one end of a normally closed auxiliary contact of a thermal element 21 with overcurrent constant value regulation, the other end of the normally closed auxiliary contact of the thermal element 21 with overcurrent constant value regulation is connected with the output null wire end of the single-phase 2P circuit breaker 9 with overcurrent protection to form an inductance loop, the signal output ends of a slag removal position inductance type proximity switch 14, an upper limit position inductance type proximity switch 15, a middle position inductance type proximity switch 16 and a lower limit position inductance type proximity switch 17 are respectively connected with the switching value input end of a programmable logic PLC controller 10, the input power ends of a deslagging position inductive proximity switch 14, an upper limit position inductive proximity switch 15, a middle position inductive proximity switch 16 and a lower limit position inductive proximity switch 17 are connected with a self-generated 24V power supply of a programmable logic PLC (programmable logic controller) 10, the anode of the self-generated 24V power supply of the programmable logic PLC 10 is connected with one end of a contact of a mode switching handle 6, the other end of the contact of the mode switching handle 6 is connected with the switching value input end of the programmable logic PLC 10, the anode of the self-generated 24V power supply of the programmable logic PLC 10 is connected with one end of a contact of a pedal self-reset switch 18, the other end of the contact of the pedal self-reset switch 18 is connected with the switching value input end of the programmable logic PLC 10, the switching value output end of the programmable logic PLC 10 is respectively connected with an operation indicator lamp 1, a fault indicator lamp 2, an alarm buzzer 3 and a cutter lifting middle relay 12 coil, One end of a coil of a cutter descending intermediate relay 13 is connected, one end of a running indicator lamp 1, a fault indicator lamp 2, an alarm buzzer 3, a coil of a cutter ascending intermediate relay 12, the other end of the coil of the cutter descending intermediate relay 13 is connected with a cathode of a self-produced 24V power supply of a programmable logic PLC (programmable logic controller) 10 to form a loop, an output live wire end of a single-phase 2P circuit breaker 9 with overcurrent protection is connected with one end of an auxiliary contact of the cutter ascending intermediate relay 12 and the cutter descending intermediate relay 13, the other end of the auxiliary contact of the cutter ascending intermediate relay 12 and the cutter descending intermediate relay 13 is connected with one end of a coil of a cutter ascending electromagnetic valve 19 and a coil of a cutter descending electromagnetic valve 20, and the other end of the coil of the cutter ascending electromagnetic valve 19 and the coil of the cutter descending electromagnetic valve 20 are connected with an output end of the single-phase 2P circuit breaker 9 with overcurrent protection to form the loop.

Firstly, three circuit breakers 7, 8 and 9 and thermal elements 21 of different types are arranged on a power supply circuit, so that the overvoltage, overcurrent and leakage protection functions of equipment are realized, and the safety of the equipment and personnel can be effectively ensured by the method for redundantly configuring the circuit breakers; then using the programmable PLC controller 10 as the control core of the whole system, and using the state of the mode switching handle 6, the state of the thermal element 21, the on-off state of the pedal plate 18 and the states of the inductive PNP type proximity switches 14, 15, 16 and 17 as the input conditions of the controller, and accessing the input conditions into the opening module of the PLC controller 10; then, logic design and program compiling are carried out, according to different working conditions and different conditions, the PLC 10 performs different actions, the specific logic is as shown in a ladder diagram in figure 3, after the hydraulic pump is electrified for the first time, no matter the cutter is at any position, the cutter should execute an initialization centering command, preparation is made for next-step groove work, when the mode switching handle 6 is switched to a normal working mode, the pedal is stepped on by a foot, the cutter moves downwards from a middle position, namely the cutter descending intermediate relay 13 is powered on, the auxiliary contact controls the cutter descending electromagnetic valve 20 to act, when the lower limit 17 is reached, the cutter returns to move to the upper limit 15, even if the cutter ascending intermediate relay 12 is powered on, the auxiliary contact controls the cutter ascending electromagnetic valve 19 to act, and finally the cutter descends to the middle position 16 to stop, and one full-stroke action is completed; when the mode switching handle 6 is switched to a cutter lifting deslagging mode, the cutter can be automatically lifted to a proximity switch (deslagging position) 14 no matter where the cutter is, and when the deslagging operation is completed, the mode switching handle 6 is switched to a normal operation mode again, the cutter can be automatically initialized to be in the middle; and finally, necessary electrical and mechanical protection logic and alarm reminding functions are added, equipment damage is effectively prevented, when the cutter is electrified and initialized to return to the middle process or after one-time full-stroke cutting is completed, if the cutter does not return to the middle position 16 within 8 seconds from the beginning of action, the cutter stops giving commands of ascending and descending, meanwhile, the fault lamp 2 is lightened and the buzzer 3 is driven to buzz to remind an operator to check, the fault lamp can be extinguished after the fault is eliminated, otherwise, the buzzer is always lightened, the buzzer buzzes within 20 seconds after the fault is eliminated, and the buzzing stops after the fault exceeds 20 seconds. Through these functions, can effectively avoid the motor overload operation and the long-time electrified equipment injury that causes of solenoid valve.

Example 1

One repair and distribution class for company maintenance has a beveling machine, an electric control system of the beveling machine adopts a pure contactor control mode, loop formation and wiring are complicated, the operation flow of the machine is complicated, the protection function of a hydraulic station motor and an electromagnetic valve is lacked, equipment faults occur frequently, an electromagnetic valve coil is frequently damaged, in addition, the control system has no operation state and fault indication, and human-computer interaction is extremely unfriendly.

Aiming at the situation, the utility model people decide to firstly apply the utility model technology to the beveling machine, firstly, the original old control system wiring is completely removed, and finally, the automatic components only leave the electromagnetic valve for executing the ascending and descending of the cutter; then, the installation and wiring of the components of the automatic control system cabinet are completed according to the configuration modes of figures 2-4; then, the assembled control cabinet is brought to the site and is connected with an automatic component which is not in the control cabinet, namely, the output signals of proximity switches and pedal switch signals at 4 positions are respectively connected to the input end of the switching value of a programmable PLC controller, one end of an auxiliary contact of a cutter lifting intermediate relay and a cutter lowering intermediate relay is connected with one end of a cutter lifting electromagnetic valve and one end of a cutter lowering electromagnetic valve coil, the other ends of the cutter lifting electromagnetic valve and the cutter lowering electromagnetic valve coil are connected with the output zero line end of a single-phase 2P circuit breaker with overcurrent protection to form a loop, in addition, the lower output end of a thermal element with overcurrent constant value regulation is directly connected with a hydraulic pump motor, and thus, the automatic control system is seamlessly applied to the beveling machine; and finally, the groove machine can smoothly complete groove work through field tests, the groove efficiency is greatly improved compared with that before modification, the end face of the groove is smooth and neat, and the groove requirement is met. The newly-added cutter lifting deslagging mode is very good in use, and great convenience is brought to the operation of cleaning the cutting slag by operators. Through the manual oil pressure that reduces, the cutter time-out trouble in returning to the well is simulated, and whole system stops to operate, and the action result satisfies the design requirement, in addition, simulates all fault signals, trouble lamp and bee calling organ homoenergetic and normally work. The automatic control system is used for 5 months after being automatically put into use, and after the machine works in the face of a centralized pipeline groove, the machine still has no fault, so that the stability and the reliability of the operation of the machine are greatly improved.

Claims

1. An automatic control system for a pipeline groove is characterized in that: the automatic control system comprises a hydraulic pump starting self-reset button (4), a hydraulic pump stopping self-reset button (5), a mode switching handle (6), a three-phase 3P circuit breaker (7) with overvoltage, overcurrent and electric leakage protection, a three-phase 3P circuit breaker (8) with overcurrent protection, a single-phase 2P circuit breaker (9) with overcurrent protection, a PLC (programmable logic controller) controller (10), a hydraulic pump starting contactor (11), a cutter lifting intermediate relay (12), a cutter descending intermediate relay (13), a cutter lifting electromagnetic valve (19), a cutter descending electromagnetic valve (20) and a thermal element (21) with overcurrent fixed value adjustment, wherein the three-phase 3P circuit breaker (7) with overvoltage, overcurrent and electric leakage protection is connected with a three-phase alternating current inlet wire main power supply and the three-phase 3P circuit breaker (8) with overcurrent protection, and the three-phase 3P circuit breaker (8) with overcurrent protection is connected with the hydraulic pump starting contactor (11), the hydraulic pump starting contactor (11) is connected with a thermal element (21) with overcurrent constant value regulation, the thermal element (21) with overcurrent constant value regulation is connected with a hydraulic pump motor, the output lower end of a three-phase 3P circuit breaker (7) with overvoltage overcurrent and leakage protection is connected with a single-phase 2P circuit breaker (9) with overcurrent protection by taking an alternating current 220V control power supply composed of a single-phase power supply and a zero line, the single-phase 2P circuit breaker (9) with overcurrent protection is connected with a PLC (programmable logic controller) (10), the single-phase 2P circuit breaker (9) with overcurrent protection is connected with a hydraulic pump self-resetting button (4), the hydraulic pump starting self-resetting button (4) is connected with a hydraulic pump stopping self-resetting button (5), the hydraulic pump stopping self-resetting button (5) is connected with a hydraulic pump starting contactor (11) coil, and the hydraulic pump starting contactor (11) coil is connected with an auxiliary contact of the thermal element (21) with overcurrent constant value regulation, the auxiliary contact of the thermal element (21) with the overcurrent constant value regulation is connected with the output zero line end of the single-phase 2P circuit breaker (9) with the overcurrent protection to form a loop, the PLC (10) is connected with one end of a coil of a cutter ascending intermediate relay (12) and one end of a coil of a cutter descending intermediate relay (13), the utility model discloses a single-phase 2P circuit breaker (9) output live wire end with overcurrent protection rises auxiliary relay (12) with the cutter, the one end of the auxiliary contact of cutter decline auxiliary relay (13) links to each other, cutter rise auxiliary relay (12), the other end of the auxiliary contact of cutter decline auxiliary relay (13) rises solenoid valve (19) with the cutter, cutter decline solenoid valve (20) coil one end links to each other, cutter rise solenoid valve (19), cutter decline solenoid valve (20) coil other end all links to each other with the single-phase 2P circuit breaker (9) output zero line end that has overcurrent protection and constitutes the return circuit.

2. The automatic control system for the pipe beveling of claim 1 wherein: the system also comprises a deslagging position inductive proximity switch (14), an upper limit position inductive proximity switch (15), a middle position inductive proximity switch (16), a lower limit position inductive proximity switch (17) and a pedal self-reset switch (18), wherein the signal output ends of the deslagging position inductive proximity switch (14), the upper limit position inductive proximity switch (15), the middle position inductive proximity switch (16) and the lower limit position inductive proximity switch (17) are respectively connected with the switching value input end of the PLC controller (10), the input power ends of the deslagging position inductive proximity switch (14), the upper limit position inductive proximity switch (15), the middle position inductive proximity switch (16) and the lower limit position inductive proximity switch (17) are connected with a self-produced 24V power supply of the PLC controller (10), the anode of the self-produced 24V power supply of the PLC controller (10) is connected with one end of a contact of the mode switching handle (6), the other end of the contact of the mode switching handle (6) is connected with the input end of the switching value of the PLC (10), the anode of a 24V power supply self-produced by the PLC (10) is connected with one end of the contact of the pedal self-reset switch (18), and the other end of the contact of the pedal self-reset switch (18) is connected with the input end of the switching value of the PLC (10).

3. The automatic control system for the pipe beveling of claim 1 wherein: the system further comprises an operation indicator lamp (1), a fault indicator lamp (2) and an alarm buzzer (3), wherein the operation indicator lamp (1), the fault indicator lamp (2) and the alarm buzzer (3) are connected with the switching value output end of the PLC (10).

4. The automatic control system for the pipe beveling of claim 1 wherein: the output lower end of the three-phase 3P circuit breaker (7) with overvoltage, overcurrent and leakage protection is connected with a single-phase 2P circuit breaker (9) with overcurrent protection, and an alternating current 220V control power supply consisting of a single-phase power supply and a zero line is connected with the zero line.