System and method for preventing hydraulic steel pulling weakness of steel splitting roller way

Abstract

The invention discloses a method for preventing hydraulic steel pulling weakness of a steel splitting roller way, relates to the field of steel splitting, and solves the technical problem that a steel pulling claw acts slowly and weakly due to the fact that a contact of an existing intermediate relay is prone to adhesion. The system comprises a control circuit used for controlling each intermediate relay; and the main circuit is used for controlling the intermediate relay in the action process according to the corresponding control circuit. The invention further discloses a system for preventing hydraulic steel pulling weakness of the steel splitting roller way. The situation that the actual action is not completely stopped due to the fact that single contacts are prone to adhesion can be prevented.

Description

Technical Field

[0001] The invention relates to the field of steel separation, and more particularly to a system and method for preventing hydraulic steel pulling failure of a steel separation roller. Background Art

[0002] like Figure 1 As shown, the existing technical status is as follows: the existing rolling mill double-high-line steel-dividing roller table divides steel through a hydraulic system, and the billets from the rough rolling single line are divided into two lines on the steel-dividing roller table. There are a total of four commands: the first line steel-pulling claw is raised, the first line steel-pulling claw is lowered, the second line steel-pulling claw is raised, and the second line steel-pulling claw is lowered. Among them, the above four commands are controlled by four process intermediate relays respectively. The first line steel-pulling claw raising process is controlled by the first line pulling up intermediate relay, the first line steel-pulling claw lowering process is controlled by the first line lowering intermediate relay, the second line steel-pulling claw raising process is controlled by the second line pulling up intermediate relay, and the second line steel-pulling claw lowering process is controlled by the second line lowering intermediate relay.

[0003] The on and off of the coil of the first-line intermediate relay is controlled by the first intermediate relay, the on and off of the coil of the first-line intermediate relay is controlled by the second intermediate relay, the on and off of the coil of the second-line intermediate relay is controlled by the third intermediate relay, and the on and off of the coil of the second-line intermediate relay is controlled by the fourth intermediate relay.

[0004] Under the existing technical conditions, after the four actions are instructed, the contacts of each intermediate relay are prone to sticking, resulting in the actual action not being completely terminated. When the valve station continues to operate in the reverse direction, the position of the valve core of the valve station will be uncertain under the combined action of both directions, resulting in the phenomenon that the steel claw moves slowly and weakly. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a system for preventing hydraulic steel pulling from being weak in view of the deficiencies in the prior art, thereby solving the technical problem that the contacts of the existing intermediate relay are prone to adhesion, which causes the steel pulling claws to move slowly and weakly.

[0006] The invention discloses a method for preventing hydraulic steel pulling failure of a steel dividing roller table. The method comprises connecting a redundant relay which acts synchronously with the intermediate relay in parallel to the intermediate relay of the control circuit of the first-line steel pulling claw and the second-line steel pulling claw.

[0007] As a further improvement, a freewheeling diode is connected between the two ends of the intermediate relay coil of the main circuit of the first-line steel-pulling claw and the second-line steel-pulling claw.

[0008] According to the above-mentioned system for preventing hydraulic steel pulling failure of a steel dividing roller table, the system includes a control circuit and a main circuit, and the control circuit includes a first control subcircuit, a second control subcircuit, a third control subcircuit and a fourth control subcircuit;

[0009] The main circuit includes a first sub-circuit, a second sub-circuit, a third sub-circuit and a fourth sub-circuit.

[0010] As a further improvement, the first control subcircuit includes a first intermediate relay and a fifth intermediate relay, the coil of the first intermediate relay and the coil of the fifth intermediate relay are connected in parallel, and the coil of the first intermediate relay is connected to the controller.

[0011] Furthermore, the first subcircuit includes a sixth intermediate relay, a second intermediate relay and a first-line pull-out intermediate relay, one end of the coil of the first-line pull-out intermediate relay is connected to the power supply through the normally open contact of the fifth intermediate relay and the normally open contact of the first intermediate relay connected in series, the other end of the coil of the first-line pull-out intermediate relay is connected to the power supply through the normally closed contact of the sixth intermediate relay and the normally closed contact of the second intermediate relay connected in series, and a first freewheeling diode is connected between the two ends of the coil of the first-line pull-out intermediate relay.

[0012] Furthermore, the second control subcircuit includes a second intermediate relay and a sixth intermediate relay, the coil of the second intermediate relay and the coil of the sixth intermediate relay are connected in parallel, and the coil of the second intermediate relay is connected to the controller.

[0013] Furthermore, the second sub-circuit includes a fifth intermediate relay, a first intermediate relay and a one-line drop intermediate relay, one end of the coil of the one-line drop intermediate relay is connected to the power supply through the normally open contact of the sixth intermediate relay and the normally open contact of the second intermediate relay connected in series, the other end of the coil of the one-line pull-up intermediate relay is connected to the power supply through the normally closed contact of the fifth intermediate relay and the normally closed contact of the first intermediate relay connected in series, and a second freewheeling diode is connected between the two ends of the coil of the one-line drop intermediate relay.

[0014] Furthermore, the third control subcircuit includes a third intermediate relay and a seventh intermediate relay, the coil of the third intermediate relay and the coil of the seventh intermediate relay are connected in parallel, and the coil of the third intermediate relay is connected to the controller.

[0015] Furthermore, the third sub-circuit also includes an eighth intermediate relay, a fourth intermediate relay and a two-wire pull-up intermediate relay, one end of the coil of the two-wire pull-up intermediate relay is connected to the power supply through the normally open contact of the seventh intermediate relay and the normally open contact of the third intermediate relay connected in series, the other end of the coil of the two-wire pull-up intermediate relay is connected to the power supply through the normally closed contact of the eighth intermediate relay and the normally closed contact of the fourth intermediate relay connected in series, and a third freewheeling diode is connected between the two ends of the coil of the two-wire pull-up intermediate relay.

[0016] Furthermore, the fourth control subcircuit includes a fourth intermediate relay and an eighth intermediate relay, the coil of the fourth intermediate relay and the coil of the eighth intermediate relay are connected in parallel, and the coil of the fourth intermediate relay is connected to the controller;

[0017] The fourth subcircuit includes a seventh intermediate relay, a third intermediate relay and a two-line drop intermediate relay. One end of the coil of the two-line drop intermediate relay is connected to the power supply through the normally open contact of the eighth intermediate relay and the normally open contact of the fourth intermediate relay connected in series, and the other end of the coil of the two-line drop intermediate relay is connected to the power supply through the normally closed contact of the seventh intermediate relay and the normally closed contact of the third intermediate relay connected in series. A fourth freewheeling diode is connected between the two ends of the coil of the two-line drop intermediate relay.

[0018] Beneficial Effects

[0019] The advantages of the present invention are:

[0020] 1. The present invention sets up a control circuit and a main circuit, and adds an intermediate relay coil and an intermediate relay contact on the basis of the original control by a single intermediate relay and an intermediate relay contact in each action process, and adopts a normally open and normally closed contact interlocking structure, which can prevent a single contact from sticking and avoid the situation where the actual action is not completely terminated.

[0021] 2. In the present invention, a freewheeling diode is connected between the two ends of the coil of the intermediate relay in the main circuit to protect the contacts of the intermediate relay from being burned by electric sparks. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 An electrical schematic diagram of the existing control circuit and main circuit;

[0023] Figure 2 is an electrical schematic diagram of a first control subcircuit of the present invention;

[0024] Figure 3 is an electrical schematic diagram of a second control subcircuit of the present invention;

[0025] Figure 4 is an electrical schematic diagram of a third control subcircuit of the present invention;

[0026] Figure 5 This is an electrical schematic diagram of the fourth control subcircuit of the present invention.

[0027] Among them: KA1- pull up the first line intermediate relay, KA2- drop the first line intermediate relay, KA3- pull up the second line intermediate relay, KA4- drop the second line intermediate relay, KM1- the first intermediate relay, KM2- the second intermediate relay, KM3- the third intermediate relay, KM4- the fourth intermediate relay, KM5- the fifth intermediate relay, KM6- the sixth intermediate relay, KM7- the seventh intermediate relay, KM8- the eighth intermediate relay, D- freewheeling diode. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0029] See also Figure 2-Figure 5 The present invention discloses a system for preventing hydraulic steel pulling roller from being weak. The system comprises a control circuit and a main circuit. The control circuit comprises a first control subcircuit, a second control subcircuit, a third control subcircuit and a fourth control subcircuit.

[0030] like Figure 2 As shown, the first control subcircuit includes a coil of a first intermediate relay KM1 and a coil of a fifth intermediate relay KM5, the coil of the first intermediate relay KM1 and the coil of the fifth intermediate relay KM5 are connected in parallel, and the coil of the first intermediate relay KM1 is connected to the controller.

[0031] like Figure 3 As shown, the second control subcircuit includes a coil of a second intermediate relay KM2 and a coil of a sixth intermediate relay KM6, the coil of the second intermediate relay KM2 and the coil of the sixth intermediate relay KM6 are connected in parallel, and the coil of the second intermediate relay KM2 is connected to the controller.

[0032] like Figure 4 As shown, the third control subcircuit includes a coil of a third intermediate relay KM3 and a coil of a seventh intermediate relay KM7, the coil of the third intermediate relay KM3 and the coil of the seventh intermediate relay KM7 are connected in parallel, and the coil of the third intermediate relay KM3 is connected to the controller.

[0033] like Figure 5As shown, the fourth control subcircuit includes a coil of a fourth intermediate relay KM4 and a coil of an eighth intermediate relay KM8, the coil of the fourth intermediate relay KM4 and the coil of the eighth intermediate relay KM8 are connected in parallel, and the coil of the fourth intermediate relay KM4 is connected to the controller.

[0034] like Figure 2-5 As shown, the main circuit is used to control the intermediate relay during the action process according to the corresponding control circuit. The main circuit includes a first sub-circuit, a second sub-circuit, a third sub-circuit and a fourth sub-circuit.

[0035] like Figure 2 As shown, the first subcircuit includes the normally open contact of the fifth intermediate relay KM5, the normally open contact of the first intermediate relay KM1, the normally closed contact of the sixth intermediate relay KM6, the normally closed contact of the second intermediate relay KM2 and the coil of the one-wire pull-out intermediate relay KA1, one end of the coil of the one-wire pull-out intermediate relay KA1 is connected to the power supply through the normally open contact of the fifth intermediate relay KM5 and the normally open contact of the first intermediate relay KM1 connected in series, and the other end of the coil of the one-wire pull-out intermediate relay KA1 is connected to the power supply through the normally closed contact of the sixth intermediate relay KM6 and the normally closed contact of the second intermediate relay KM2 connected in series. A first freewheeling diode D1 is connected between the two ends of the coil of the one-wire pull-out intermediate relay KA1.

[0036] like Figure 3 As shown, the second subcircuit includes the normally open contact of the sixth intermediate relay KM6, the normally open contact of the second intermediate relay KM2, the normally closed contact of the fifth intermediate relay KM5, the normally closed contact of the first intermediate relay KM1 and the coil of the one-line drop intermediate relay KA2, one end of the coil of the one-line drop intermediate relay KA2 is connected to the power supply through the normally open contact of the sixth intermediate relay KM6 and the normally open contact of the second intermediate relay KM2 connected in series, and the other end of the coil of the one-line pull-up intermediate relay KA1 is connected to the power supply through the normally closed contact of the fifth intermediate relay KM5 and the normally closed contact of the first intermediate relay KM1 connected in series. A second freewheeling diode D2 is connected between the two ends of the coil of the one-line drop intermediate relay KA2.

[0037] like Figure 4As shown, the third sub-circuit includes the normally open contact of the seventh intermediate relay KM7, the normally open contact of the third intermediate relay KM3, the normally closed contact of the eighth intermediate relay KM8, the normally closed contact of the fourth intermediate relay KM4 and the coil of the two-line pull-up intermediate relay KA3, one end of the coil of the two-line pull-up intermediate relay KA3 is connected to the power supply through the normally open contact of the seventh intermediate relay KM7 and the normally open contact of the third intermediate relay KM3 connected in series, and the other end of the coil of the two-line pull-up intermediate relay KA3 is connected to the power supply through the normally closed contact of the eighth intermediate relay KM8 and the normally closed contact of the fourth intermediate relay KM4 connected in series. A third freewheeling diode D3 is connected between the two ends of the coil of the two-line pull-up intermediate relay KA3.

[0038] like Figure 5 As shown, the fourth subcircuit includes the normally open contact of the eighth intermediate relay KM8, the normally open contact of the fourth intermediate relay KM4, the normally closed contact of the seventh intermediate relay KM7, the normally closed contact of the third intermediate relay KM3 and the coil of the second-line drop intermediate relay KA4, one end of the coil of the second-line drop intermediate relay KA4 is connected to the power supply through the normally open contact of the eighth intermediate relay KM8 and the normally open contact of the fourth intermediate relay KM4 connected in series, and the other end of the coil of the second-line drop intermediate relay KA4 is connected to the power supply through the normally closed contact of the seventh intermediate relay KM7 and the normally closed contact of the third intermediate relay KM3 connected in series. A fourth freewheeling diode D4 is connected between the two ends of the coil of the second-line drop intermediate relay KA4. The freewheeling diode is used to protect the contacts of the intermediate relay from being burned by electric sparks during the action process.

[0039] The voltage of the power supply is 24V.

[0040] A method for preventing hydraulic steel pulling failure according to the above-mentioned steel roller table system,

[0041] Step 1: Find out the reason why the existing hydraulic steel pulling is weak.

[0042] The working condition of the solenoid valve with light plug of the hydraulic valve station is continuously monitored through the video surveillance camera. When the steel pulling claws of the steel separation roller are unable to pull steel, the video surveillance of the hydraulic valve station is replayed, and it is found that before the steel pulling claws are raised, the solenoid valve with light plug that the steel pulling claws fall has been in a state of slight power on.

[0043] When the MicroDian light is on: the circuit is not completely disconnected, the device still has a certain voltage and the voltage is lower than the normal working voltage.

[0044] Step 2: The hydraulic valve station works abnormally, resulting in insufficient hydraulic oil flow.

[0045] Through playback monitoring, it can be found that the solenoid valve coils on both sides of the electro-hydraulic reversing valve are energized, which will cause the valve core of the hydraulic valve station to move weakly, and then cause the hydraulic oil flow rate of the lifting oil circuit of the steel claw to decrease and the pressure to be insufficient, which eventually causes the steel pulling action to be slow and weak. The reason for the above situation is that after the coils on both sides of the electro-hydraulic reversing valve are energized, the valve core is pushed by the opposite electromagnetic forces at both ends, resulting in the valve core being unable to be controlled in place.

[0046] Electro-hydraulic reversing valve: Electro-hydraulic reversing valve is a common fluid control component that can change the direction of fluid passing through the valve according to electrical signals, thereby controlling the flow rate, flow rate and pressure of the fluid.

[0047] Step three, the coils on both sides of the hydraulic valve station are energized at the same time, and the position of the valve core of the hydraulic valve station is uncertain.

[0048] The valve core is pushed by the opposite electromagnetic forces at both ends, resulting in the valve core not being able to be controlled in place. The valve core movement is different according to the electromagnetic forces generated by the working voltages of the coils at both ends, which will cause the position of the valve core on the valve table to be uncertain, and finally lead to the phenomenon that the steel roller puller claws move slowly and weakly.

[0049] Step 4: Pull out the steel claws to remove the stuck contacts of the intermediate relay.

[0050] When the coil of the intermediate relay KA2 that drops the steel claw loses power, under normal circumstances, the normally open contact of the second intermediate relay KM2 will disconnect the circuit and drop the steel claw back. However, due to the electric spark arcing generated by the contacts during use, the contacts will be burned and cause intermittent adhesion. The circuit will still be turned on after the contacts are adhered. Oxides may exist on the contacts, thereby increasing the resistance and conducting part of the voltage, allowing the steel claw that has not yet fallen to continue to be energized and maintain the dropped state. At the same time, the electromagnet in the undervoltage state can easily cause the coil to heat up and burn out.

[0051] Step 5: Design and draw the circuit.

[0052] In order to prevent the influence of misconduction caused by contact sticking, the characteristic is enhanced by increasing the number of normally open contacts in series with the intermediate relay in the circuit design. At the same time, the principle of relative action of normally open and normally closed contacts is used for interlocking, so that the circuit can further enhance the ability to prevent misconduction caused by contact sticking.

[0053] Step six, add 4 intermediate relays according to the circuit diagram.

[0054] Reference Figure 2-5 Complete the installation of components in the electrical cabinet, install them side by side on top of the original relay, adopt the control method of connecting the new and old intermediate relay coils in parallel, and use PLC to control the synchronous action of the two intermediate relays at the same time.

[0055] Step 7. Complete the wiring according to the circuit diagram.

[0056] Reference Figure 2-5 After completing the installation of components in the electrical cabinet, wiring is carried out. During the operation process, one output end of the intermediate relay is connected in series with two normally open contacts, and the other output end is connected in series with two normally closed contacts for interlocking. At the same time, a freewheeling diode D is connected in parallel to the solenoid valve coil at the output end to protect the contacts of the intermediate relay from being burned by electric sparks.

[0057] Step 8. Test completed, test run is normal.

[0058] After the equipment transformation is completed, it is necessary to start the hydraulic station of the steel separation roller table steel claw, set the start authority to the local mode, and complete the operation on site:

[0059] When the lifting action of the steel claw is required, the coil of the first intermediate relay KM1 and the coil of the fifth intermediate relay KM5 are energized;

[0060] When the coils of the first intermediate relay KM1 and the fifth intermediate relay KM5 are energized, the normally open contacts of the fifth intermediate relay KM5 and the normally open contacts of the first intermediate relay KM1 are closed at the same time, the normally closed contacts of the fifth intermediate relay KM5 and the normally closed contacts of the first intermediate relay KM1 are opened at the same time, the coil of the one-wire pulling intermediate relay KA1 is energized, and the one-wire pulling claw lifting action begins.

[0061] When the one-wire steel claw needs to drop, the coil of the second intermediate relay KM2 and the coil of the sixth intermediate relay KM6 are energized;

[0062] When the coil of the second intermediate relay KM2 and the coil of the sixth intermediate relay KM6 are energized, the normally open contacts of the second intermediate relay KM2 and the normally open contacts of the sixth intermediate relay KM6 are closed at the same time, the normally closed contacts of the second intermediate relay KM2 and the normally closed contacts of the sixth intermediate relay KM6 are opened at the same time, the coil of the one-wire falling intermediate relay KA2 is energized, and the one-wire steel claw falling action begins.

[0063] When the two-wire steel claw lifting action is required, the coil of the third intermediate relay KM3 and the coil of the seventh intermediate relay KM7 are energized;

[0064] When the coil of the third intermediate relay KM3 and the coil of the seventh intermediate relay KM7 are energized, the normally open contacts of the third intermediate relay KM3 and the normally open contacts of the seventh intermediate relay KM7 are closed at the same time, the normally closed contacts of the third intermediate relay KM3 and the normally closed contacts of the seventh intermediate relay KM7 are opened at the same time, the coil of the two-wire pulling intermediate relay KA3 is energized, and the two-wire pulling claw lifting action begins.

[0065] When the two-wire steel claws need to drop, the coil of the fourth intermediate relay KM4 and the coil of the eighth intermediate relay KM8 are energized;

[0066] When the coil of the fourth intermediate relay KM4 and the coil of the eighth intermediate relay KM8 are energized, the normally open contacts of the fourth intermediate relay KM4 and the normally open contacts of the eighth intermediate relay KM8 are closed at the same time, the normally closed contacts of the fourth intermediate relay KM4 and the normally closed contacts of the eighth intermediate relay KM8 are opened at the same time, the coil of the two-wire falling intermediate relay KA4 is energized, and the two-wire steel claw falling action begins.

[0067] Finally, test whether the steel pulling claws of the first line and the second line are pulled up and down normally, and whether the contacts of the intermediate relay produce obvious electric sparks or other arcing phenomena.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for preventing hydraulic steel pulling failure by a steel separation roller, characterized in that: The method comprises the following steps: connecting a redundant relay which acts synchronously with the intermediate relay in parallel to the intermediate relay of the control circuit of the first-line steel-pulling claw and the second-line steel-pulling claw.

2. The method for preventing hydraulic steel pulling failure of a steel separation roller according to claim 1 is characterized in that: A freewheeling diode is connected between the two ends of the intermediate relay coil of the main circuit of the first-line steel-pulling claw and the second-line steel-pulling claw.

3. A system for preventing hydraulic steel pulling failure of a steel separation roller according to any one of claims 1-2, characterized in that: The system comprises a control circuit and a main circuit, wherein the control circuit comprises a first control subcircuit, a second control subcircuit, a third control subcircuit and a fourth control subcircuit; The main circuit includes a first sub-circuit, a second sub-circuit, a third sub-circuit and a fourth sub-circuit.

4. The system for preventing hydraulic steel pulling failure of a steel separation roller table according to claim 3 is characterized in that: The first control subcircuit comprises a first intermediate relay (KM1) and a fifth intermediate relay (KM5), the coil of the first intermediate relay (KM1) and the coil of the fifth intermediate relay (KM5) are connected in parallel, and the coil of the first intermediate relay (KM1) is connected to a controller.

5. The system for preventing hydraulic steel pulling failure of a steel separation roller table according to claim 4 is characterized in that: The first subcircuit comprises a sixth intermediate relay (KM6), a second intermediate relay (KM2) and a first-line pull-out intermediate relay (KA1); one end of the coil of the first-line pull-out intermediate relay (KA1) is connected to a power supply via a normally open contact of a fifth intermediate relay (KM5) and a normally open contact of the first intermediate relay (KM1) connected in series; the other end of the coil of the first-line pull-out intermediate relay (KA1) is connected to a power supply via a normally closed contact of a sixth intermediate relay (KM6) and a normally closed contact of the second intermediate relay (KM2) connected in series; and a first freewheeling diode (D1) is connected between the two ends of the coil of the first-line pull-out intermediate relay (KA1).

6. The system for preventing hydraulic steel pulling failure of a steel separation roller table according to claim 3 is characterized in that: The second control subcircuit comprises a second intermediate relay (KM2) and a sixth intermediate relay, the coil of the second intermediate relay (KM2) and the coil of the sixth intermediate relay (KM6) are connected in parallel, and the coil of the second intermediate relay (KM2) is connected to a controller.

7. The system for preventing hydraulic steel pulling failure of a steel separation roller table according to claim 6 is characterized in that: The second sub-circuit comprises a fifth intermediate relay (KM5), a first intermediate relay (KM1) and a one-wire drop intermediate relay (KA2); one end of the coil of the one-wire drop intermediate relay (KA2) is connected to the power supply via a normally open contact of a sixth intermediate relay (KM6) and a normally open contact of a second intermediate relay (KM2) connected in series; the other end of the coil of the one-wire pull-up intermediate relay (KA1) is connected to the power supply via a normally closed contact of a fifth intermediate relay (KM5) and a normally closed contact of the first intermediate relay (KM1) connected in series; and a second freewheeling diode (D2) is connected between the two ends of the coil of the one-wire drop intermediate relay (KA2).

8. The system for preventing hydraulic steel pulling failure of a steel separation roller table according to claim 3 is characterized in that: The third control subcircuit comprises a third intermediate relay (KM3) and a seventh intermediate relay (KM7), the coil of the third intermediate relay (KM3) and the coil of the seventh intermediate relay (KM7) are connected in parallel, and the coil of the third intermediate relay (KM3) is connected to a controller.

9. A system for preventing hydraulic steel pulling failure of a steel separation roller table according to claim 8, characterized in that: The third subcircuit comprises an eighth intermediate relay (KM8), a fourth intermediate relay (KM4) and a two-wire pull-up intermediate relay (KA3); one end of the coil of the two-wire pull-up intermediate relay (KA3) is connected to a power supply via a normally open contact of a seventh intermediate relay (KM7) and a normally open contact of a third intermediate relay (KM3) connected in series; the other end of the coil of the two-wire pull-up intermediate relay (KA3) is connected to a power supply via a normally closed contact of an eighth intermediate relay (KM8) and a normally closed contact of a fourth intermediate relay (KM4) connected in series; and a third freewheeling diode (D3) is connected between the two ends of the coil of the two-wire pull-up intermediate relay (KA3).

10. The system for preventing hydraulic steel pulling failure of a steel separation roller table according to claim 3 is characterized in that: The fourth control subcircuit comprises a fourth intermediate relay (KM4) and an eighth intermediate relay (KM8), the coil of the fourth intermediate relay (KM4) and the coil of the eighth intermediate relay (KM8) are connected in parallel, and the coil of the fourth intermediate relay (KM4) is connected to a controller; The fourth subcircuit includes a seventh intermediate relay (KM7), a third intermediate relay (KM3) and a two-wire drop intermediate relay (KA4); one end of the coil of the two-wire drop intermediate relay (KA4) is connected to a power supply via a normally open contact of an eighth intermediate relay (KM8) and a normally open contact of a fourth intermediate relay (KM4) connected in series; the other end of the coil of the two-wire drop intermediate relay (KA4) is connected to a power supply via a normally closed contact of a seventh intermediate relay (KM7) and a normally closed contact of a third intermediate relay (KM3) connected in series; and a fourth freewheeling diode (D4) is connected between the two ends of the coil of the two-wire drop intermediate relay (KA4).

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