CN105337215A - Tool and method for replacing earth electrode circuit corner tension-resistant hardware fitting - Google Patents

Abstract

The invention discloses a tool and method for replacing the corner tension-resistant fittings of grounding pole lines, which include a front clamp, a rear clamp and a thread tightening screw rod, the front clamp is set as two hanging rings, and the hanging ring is set as "U "shape, one end of the hanging ring is fixedly connected with the cross arm, one end of the rear card is connected with the triangular connecting plate, the tightening screw is arranged between the hanging ring and the rear card, and the tightening screw includes a thrust bearing , a handle, a lead screw, a ratchet sleeve and a bearing seat, the thrust bearing is fixedly connected to the other end of the hanging ring, the handle is arranged in the middle of the lead screw, and the ratchet sleeve is arranged between the lead screw and the bearing seat Connected to the outside of the lead screw, the ratchet sleeve is fixedly connected to the bearing seat, and the bearing seat is fixedly connected to the other end of the rear card. The hanging ring, the rear card and the tightening screw are all made of high-strength steel . The invention not only has strong versatility and simple and convenient operation method, but also greatly reduces the workload of live workers on the tower and improves the operation efficiency.

Description

Tool and method for replacing grounding electrode line corner tension fittings

technical field

The invention relates to an electric power working tool, in particular to a tool and a method for replacing a corner tension fitting of a ground electrode line.

Background technique

With the rapid development of my country's economy, UHVDC transmission technology has attracted much attention because it can meet the long-distance and large-capacity power supply needs. Common DC transmission systems have two operating modes: unipolar operating mode and bipolar operating mode, in which the unipolar operating mode is divided into the metal loop mode and the earth (or seawater) as the unipolar-earth loop mode. When operating in the mode of extremely large earth loop, the entire system current flows through the earth loop; under normal conditions for bipolar lines, only unbalanced current flows through the earth loop (the value is about 1% of the rated current), but when a wire Or when a group of converter valves fails, the DC system can use the earth as a loop for unipolar operation. In order to reduce the impact of the ground current on the power equipment of the converter station, the ground electrode is generally arranged far away from the converter station. The distance can reach tens to hundreds of kilometers. The grounding pole line is the line connecting the converter station and the grounding pole line (usually an overhead line), and its safe and stable operation is crucial to the entire DC system.

Due to the characteristics of the line structure of the grounding pole line, the overhead line from the converter station to the grounding pole site generally cannot be reached along a straight line, and needs to meander to avoid other line corridors, so corner towers are often used, and the fitting structure of the corner tower and Other types of towers are quite different, so there is no special tool to replace their hardware.

The notification number CN103500961A discloses a special tool for live replacement of tension insulator strings, which includes two insulating ropes arranged in parallel. The twisted lead screw is connected to the front end of the insulating rope, the left and right ends of the rear card are connected to the rear end of the insulating rope, and a middle card is arranged in front of the rear card between the two insulating ropes, and a receiving card is provided at the left and right ends of the middle card respectively. The tightening screw is connected to the rear card, the rear side of the front card is connected to the tension insulator through the connecting plate, and the front side of the rear card is connected to the tensile insulator through the connecting plate. This special tool cannot be used in the process of replacing the insulator. The adjustment of the angle can not avoid the interference of the hardware and the cross arm to the tool, and the structure of this special tool is complicated, which is inconvenient for the staff to perform the replacement operation.

Contents of the invention

In view of this, the object of the present invention is to address the deficiencies of the prior art, and provide a tool and method for replacing the corner tension fittings of the ground electrode line, which not only has strong versatility, simple and convenient operation method, light and flexible, but also greatly reduces the It reduces the workload of live operators on the tower and improves the working efficiency.

To achieve the above object, the present invention adopts the following technical solutions:

A tool for replacing the corner tension fittings of grounding electrode lines, including a front card, a rear card and a thread tightening screw rod, the front card is set as two hanging rings, the hanging ring is set in a "U" shape, and the hanging One end of the ring is fixedly connected with the cross arm, one end of the rear card is connected with the triangular connecting plate, the tightening screw is arranged between the hanging ring and the rear card, and the tightening screw includes a thrust bearing, a handle, a leading screw, A ratchet sleeve and a bearing seat, the thrust bearing is fixedly connected to the other end of the hanging ring, the handle is arranged in the middle of the screw, the ratchet sleeve is arranged between the screw and the bearing seat and is sleeved on the screw In addition, the ratchet sleeve is fixedly connected to the bearing seat, and the bearing seat is fixedly connected to the other end of the rear card. The hanging ring, the rear card and the tightening screw are all made of high-strength steel.

Preferably, the rear card is set as a joint plate rear card, and the joint plate rear card is fixedly connected to the triangular joint plate through a right-angle hanging plate.

Preferably, the rear clamp is configured as a hook rear clamp, one end of the hook rear clamp is fixedly connected to the bearing seat, and the other end is movably connected to the triangular connecting plate.

Preferably, first mounting holes for fixing to the bearing housing are respectively provided on both sides of the rear clamp of the connecting plate, and second mounting holes for fixing to the right-angle hanging plate and the triangular connecting plate are provided in the middle of the rear clamp of the connecting plate.

Preferably, one end of the rear clip of the hook is provided with a third installation hole for fixing with the bearing seat.

Preferably, the high-strength steel includes the following components in terms of weight percentage: C=0.12~0.20%, Si=1.60~1.85%, Mn=0.85~2.3%, Cr=1.85~3.12%, Ni=0.72~1.86 %, Mo=0.32~0.86%, Ti=0.08~0.12%, Nb=0.04~0.08%, V=0.12~0.19%, B=0.001~0.0022%, Tm=3.6~4.8%, S=0.002~0.010% , and the rest are iron and unavoidable impurities.

Preferably, the preparation method of the high-strength steel comprises the following steps:

(1) Weigh various raw materials, and crush and grind the bulk raw materials for 30-40 minutes;

(2) Mix all raw materials together and stir in a forced mixer for 30-45 minutes to obtain mixed raw materials;

(3) Put the mixed raw material described in step (2) into a smelting furnace for smelting at 1800-2400°C for 35-50 minutes to obtain molten steel;

(4) Pour the molten steel obtained in step (3) into the casting mold, forge at 860~910°C for 12~14 passes, cool down to 350~450°C with water at a cooling rate of 0.5~1°C/s, and then air cool to At room temperature, steel ingots are obtained;

(5) Quenching the steel ingot obtained in step (4): heating the steel ingot to 800-900°C, keeping it warm for 3-5 hours, and cooling it to room temperature in air, water or oil;

(6) Tempering the steel ingot obtained in step (5): reheat the quenched steel ingot to 550-680°C, keep it warm for 2-3 hours, and place it in air, water or oil to cool to room temperature.

A method for replacing a grounding electrode line corner tension fitting, comprising the following steps:

1) Fix one end of the front card to the construction hole of the cross arm, and the other end to the thrust bearing, then connect the bearing seat to one end of the rear card, and connect the other end of the rear card to the triangular joint plate;

2) Properly tighten the tightening screw through the handle and ensure that the front and rear ends of the tool are evenly stressed and the travel of the tightening screw is appropriate;

3) Tighten the lead screw so that the force of the line corner tension fitting is transferred to the replacement tool.

The beneficial effects of the present invention are:

1. The present invention adopts the movable design of the tightening screw rod and the front and rear clamps, so that the tightening screw rod can be deflected at different angles when it is subjected to the horizontal load of the wire, ensuring that the stress on the tightening screw rod is radial, Thereby meeting the requirements of safe operation from multiple angles and avoiding the interference and influence of fittings and crossarms on tool replacement; the present invention adopts two types of rear clamps, the joint plate rear clamp and the hook rear clamp, while ensuring convenient operation, safety and reliability. Under the premise, it can meet the replacement requirements of different types of tension fittings at different angles, greatly increasing the versatility and practicability of the replacement tools; through the installation holes added on the rear clip of the connecting plate and the rear clip of the hook, the connecting plate can be The back clip and the hook are fixed on the bearing seat and the triangular link plate, so that the post clip of the link plate, the rear clip of the hook and the tightening screw and the triangular link plate are integrated, which can effectively prevent the back clip from loosening and ensure the construction. Safe; in the present invention, the front clamp, the rear clamp and the tightening screw are all made of high-strength steel materials, and the high-strength steel replaces ordinary metal materials to improve the performance of the workpiece.

2. In the raw material of the high-strength steel of the present invention, C is used as a strengthening element, solid solution strengthening and metastable carbides can be precipitated after low-temperature tempering to achieve the purpose of strengthening; an appropriate amount of Si can be dissolved in the martensite matrix, through Solid solution strengthening improves the strength of steel; Cr is beneficial to improve the hardenability of steel, and the strength of steel is improved through solid solution strengthening; the addition of Ti, Nb or B can effectively improve the hardenability of steel, so that the steel can be quenched and It has high strength after tempering; Ni and V can refine the size of the microstructure, make the grain smaller, and further improve the strength and toughness of the steel; Mo can purify the grain boundary and inhibit the temper brittleness. Solid solution strengthening improves the strength of steel; the rare earth element Tm can be used for deoxidation, which can prevent the damage of oxygen to the properties of the alloy, and can be added in the form of an intermediate alloy during smelting; the multi-pass forging process refines the structure and grains, and through The medium temperature tempering process eliminates the internal stress of the structure, which is beneficial to increase the strength of the steel.

Description of drawings

Fig. 1 is the structural representation of embodiment 1 of the present invention;

Fig. 2 is the structural representation of embodiment 2 of the present invention;

Fig. 3 is the schematic structural view of the tightening lead screw of the present invention;

Fig. 4 is a structural schematic diagram of the hook rear card of the present invention;

Among them, 1-hanging ring, 2-tightening screw, 3-cross arm, 4-triangular connecting plate, 5-connecting plate rear clamp, 6-right angle hanging plate, 7-first installation hole, 8-second installation Hole, 9-curved hook rear card, 10-the third mounting hole, 21-thrust bearing, 22-handle, 23-leading screw, 24-ratchet sleeve, 25-bearing seat.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Among them, in the preparation method of the high-strength steel of the present invention, O and S are harmful elements, and their content must be strictly controlled in the smelting process of the high-strength steel. In the smelting process, in addition to adding deoxidizing elements such as Mn and rare earth elements Tm, the content should also be strictly controlled. The S content in molten steel or raw materials entering the converter, when using converter smelting or electric furnace smelting to add molten iron, preferably use pretreated desulfurized molten iron, while controlling the S content of the raw material into the furnace, use LF furnace refining to obtain the target O , Liquid steel with S content.

Example 1

As shown in Figures 1 and 3, a tool and method for replacing the corner tension fittings of the grounding electrode line, including a front clamp, a rear clamp and a thread tightening screw 2, wherein the rear clamp is set as a connecting plate rear clamp 5, wherein the front clamp It is set as two "U"-shaped hanging rings 1, one end of the hanging ring 1 is fixedly connected with the cross arm 3 by bolts, and the rear card 5 of the connecting plate is screwed with the right-angle hanging plate 6 and the triangular connecting plate 4 through the second installation hole 8 provided. Connection, by adding the second installation hole 8 on the back clamp 5 of the joint plate, it can be ensured that the rear clamp 5 of the joint plate is integrated with the tightening screw rod 2 and the triangular joint plate 4, which can effectively prevent the back clamp 5 of the joint plate from getting loose, ensuring construction safety.

The tightening lead screw 2 is arranged between the hanging ring 1 and the back clamp 5 of the connecting plate. The tightening lead screw 2 includes a thrust bearing 21, a handle 22, a leading screw 23, a ratchet sleeve 24 and a bearing seat 25, and the thrust bearing 21 is arranged There is a threaded hole, which is connected to the other end of the hanging ring 1 by bolts. The handle 22 is arranged in the middle of the screw 23. The ratchet sleeve 24 is arranged between the screw 23 and the bearing seat 25 and is sleeved outside the screw 23. The ratchet sleeve Pipe 24 is fixedly connected with bearing seat 25 one end by bolt, and bearing seat 25 other end is provided with threaded hole, and the first installation hole 7 that is provided with on the back card 5 of link plate is fixedly connected with link plate back card 5 by bolt.

The hanging ring 1, the back clamp 5 of the connecting plate and the tightening screw rod 2 are all made of high-strength steel material. It can be deflected at different angles when subjected to the horizontal load of the wire, ensuring that the stress on the tightening screw 2 is radial, so as to meet the requirements of safe operation from multiple angles, and avoid the interference and influence of fittings and cross arms on the replacement tool.

When this embodiment is in use:

First, the hanging ring 1 is fixedly connected to the construction hole of the cross arm 3 through bolts, and the threaded hole is provided on the thrust bearing 21 to be fixedly connected to the hanging ring 1 by bolts. The first mounting hole 7 set on the top is fixedly connected with bolts, and then the rear card 5 of the connecting plate is fixedly connected with the second mounting hole 8 provided with the right angle hanging plate 6 and the triangular connecting plate 4, and then the handle 22 is used to properly tighten the thread. Screw 2 and ensure that the front and rear ends of the fixture are evenly stressed and the stroke of the tightening screw 2 is appropriate. Finally, only the tightening screw 2 is tightened so that the force of the line corner tension fittings can be transferred to the replacement tool.

Among them, the high-strength steel includes the following components in terms of weight percentage: C=0.12%, Si=1.60%, Mn=0.85~2.3%, Cr=1.85%, Ni=0.72%, Mo=0.32%, Ti=0.08% , Nb=0.04%, V=0.12%, B=0.001%, Tm=3.6%, S=0.002%, and the rest are iron and unavoidable impurities.

The preparation method of high-strength steel comprises the following steps:

(1) Weigh various raw materials, and crush and grind the bulk raw materials for 30 minutes;

(2) Mix all raw materials together and stir in a forced mixer for 30 minutes to obtain mixed raw materials;

(3) Put the mixed raw materials in step (2) into a smelting furnace for smelting at 1800°C for 35-50 minutes to obtain molten steel;

(4) Pour the molten steel obtained in step (3) into the casting mold, forge 12 passes at 860°C, cool down to 350°C by water cooling at a cooling rate of 0.5°C/s, and then air cool to room temperature to obtain a steel ingot;

(5) Quenching the steel ingot obtained in step (4): heating the steel ingot to 800°C, keeping it warm for 3 hours, and cooling it to room temperature in air, water or oil;

(6) Tempering the steel ingot obtained in step (5): reheat the quenched steel ingot to 550° C., keep it warm for 2 hours, and place it in air, water or oil to cool to room temperature.

Example 2

The components in Embodiment 2 are the same as the high-strength steel materials used in Embodiment 1. The difference is that: as shown in Figures 2 to 4, the rear clamp is set as a hook rear clamp 9, and one end of the hook rear clamp 9 passes through the third set. Mounting hole 10 is threaded and fixedly connected with bearing seat 25. By adding a third mounting hole 10 on the hook rear clip 9, it can be ensured that the hook rear clip 9 is integrated with the tightening wire rod 2 and the triangular connecting plate 4, which can effectively prevent After the crotch, the card 9 is loosened, which ensures the construction safety, and the other end directly hooks the long side of the triangular connecting plate 4, which can avoid the influence of the large-angle rotating triangular connecting plate 4 on the fixture.

When this embodiment is in use:

First, the hanging ring 1 is fixedly connected to the construction hole of the cross arm 3 through bolts, and the threaded hole is provided on the thrust bearing 21 to be fixedly connected to the hanging ring 1 by bolts. The third mounting hole 10 provided at one end is fixedly connected by bolts, and then the other end of the hook rear clamp 9 is directly hooked to the long side of the triangular joint plate 4, and then the thread screw 2 is properly tightened by the handle 22 to ensure that the front and rear ends of the clamp are The force is uniform and the stroke of the tightening lead screw 2 is suitable. Finally, only the tightening lead screw 2 is tightened so that the tension force of the line corner tension fittings can be transferred to the replacement tool.

Example 3

The structure and method of use of embodiment 3 and embodiment 1 are roughly the same, the difference is:

Among them, the high-strength steel includes the following components in terms of weight percentage: C=0.20%, Si=1.85%, Mn=0.85~2.3%, Cr=3.12%, Ni=1.86%, Mo=0.86%, Ti=0.12% , Nb=0.08%, V=0.19%, B=0.0022%, Tm=4.8%, S=0.010%, and the rest are iron and unavoidable impurities.

The preparation method of high-strength steel comprises the following steps:

(1) Weigh various raw materials, and crush and grind the bulk raw materials for 40 minutes;

(2) Mix all raw materials together and stir in a forced mixer for 45 minutes to obtain mixed raw materials;

(3) Put the mixed raw material described in step (2) into a smelting furnace and smelt at 2400°C for 50 minutes to obtain molten steel;

(4) Pour the molten steel obtained in step (3) into the casting mold, forge 14 passes at 910°C, cool down to 450°C by water cooling at a cooling rate of 1°C/s, and then air cool to room temperature to obtain a steel ingot;

(5) Quenching the steel ingot obtained in step (4): heating the steel ingot to 900°C, keeping it warm for 5 hours, and cooling it to room temperature in air, water or oil;

(6) Tempering the steel ingot obtained in step (5): reheat the quenched steel ingot to 680° C., keep it warm for 3 hours, and place it in air, water or oil to cool to room temperature.

Example 4

Embodiment 4 is roughly the same in structure and method of use as Embodiment 1, except that:

Among them, the high-strength steel includes the following components in terms of weight percentage: C=0.18%, Si=1.68%, Mn=1.85%, Cr=2.12%, Ni=1.06%, Mo=0.53%, Ti=0.09%, Nb =0.06%, V=0.17%, B=0.0015%, Tm=3.9%, S=0.006%, and the rest are iron and unavoidable impurities.

The preparation method of high-strength steel comprises the following steps:

(1) Weigh various raw materials, and crush and grind the bulk raw materials for 36 minutes;

(2) Mix all raw materials together and stir in a forced mixer for 38 minutes to obtain mixed raw materials;

(3) Put the mixed raw material described in step (2) into a smelting furnace for smelting at 1900°C for 40 minutes to obtain molten steel;

(4) Pour the molten steel obtained in step (3) into a casting mold, forge 13 passes at 890°C, cool down to 380°C with water at a cooling rate of 0.8°C/s, and then air cool to room temperature to obtain a steel ingot;

(5) Quenching the steel ingot obtained in step (4): heating the steel ingot to 880°C, keeping it warm for 4 hours, and cooling it to room temperature in air, water or oil;

(6) Tempering the steel ingot obtained in step (5): reheat the quenched steel ingot to 590° C., keep it warm for 2 hours, and place it in air, water or oil to cool to room temperature.

Example 5

The structure and method of use of embodiment 5 and embodiment 1 are roughly the same, the difference is:

Among them, the high-strength steel includes the following components in terms of weight percentage: C=0.15%, Si=1.77%, Mn=1.68%, Cr=2.64%, Ni=1.69%, Mo=0.72%, Ti=0.12%, Nb =0.07%, V=0.15%, B=0.0017%, Tm=4.3%, S=0.007%, and the rest are iron and unavoidable impurities.

The preparation method of high-strength steel comprises the following steps:

(1) Weigh various raw materials, and crush and grind the bulk raw materials for 32 minutes;

(2) Mix all raw materials together and stir in a forced mixer for 38 minutes to obtain mixed raw materials;

(3) Put the mixed raw material described in step (2) into a smelting furnace for smelting at 2200°C for 46 minutes to obtain molten steel;

(4) Pour the molten steel obtained in step (3) into the casting mold, forge 14 passes at 880°C, cool down to 425°C by water cooling at a cooling rate of 0.8°C/s, and then air cool to room temperature to obtain a steel ingot;

(5) Quenching the steel ingot obtained in step (4): heat the steel ingot to 860°C, keep it warm for 3.5 hours, and place it in air, water or oil to cool to room temperature;

(6) Tempering the steel ingot obtained in step (5): reheat the quenched steel ingot to 650° C., keep it warm for 3 hours, and place it in air, water or oil to cool to room temperature.

Example 6

The structure and method of use of embodiment 6 and embodiment 1 are roughly the same, the difference is:

Among them, the high-strength steel includes the following components in terms of weight percentage: C=0.20%, Si=1.70%, Mn=2.2%, Cr=2.67%, Ni=1.34%, Mo=0.68%, Ti=0.09%, Nb =0.05%, V=0.17%, B=0.0019%, Tm=3.8%, S=0.0075%, and the rest are iron and unavoidable impurities.

The preparation method of high-strength steel comprises the following steps:

(1) Weigh various raw materials, and crush and grind the bulk raw materials for 34 minutes;

(2) Mix all raw materials together and stir in a forced mixer for 38 minutes to obtain mixed raw materials;

(3) Put the mixed raw material described in step (2) into a smelting furnace for smelting at 2300°C for 43 minutes to obtain molten steel;

(4) Pour the molten steel obtained in step (3) into the casting mold, forge 14 passes at 890°C, cool down to 420°C by water cooling at a cooling rate of 0.9°C/s, and then air cool to room temperature to obtain a steel ingot;

(5) Quenching the steel ingot obtained in step (4): heating the steel ingot to 880°C, keeping it warm for 5 hours, and cooling it to room temperature in air, water or oil;

(6) Tempering the steel ingot obtained in step (5): reheat the quenched steel ingot to 680° C., keep it warm for 3 hours, and place it in air, water or oil to cool to room temperature.

The properties of the high-strength steel materials prepared in Examples 1-6 of the present invention are evaluated from tensile strength R _m (MPa), yield strength R _P0.2 (MPa), elongation (%) and impact energy (-20°C, J) The test results are shown in Table 1 below.

Table 1 shows the performance parameters of high-strength steel prepared by different embodiments:

In short, the high-strength steel produced by the present invention has high strength and toughness, and is not prone to fracture and plastic deformation; in addition, due to the high strength and toughness of the steel, it is beneficial to reduce the amount of steel used in the components, thereby reducing the cost of replacing the ground electrode circuit in the present invention. The manufacturing cost and weight of the tool of corner tension-resistant metal fittings greatly improve the impact resistance and fracture toughness of the replacement tool. At the same time, the steel has excellent fatigue strength and wear resistance, which greatly improves the service life of the replacement tool. ; And, the present invention replaces the tool of ground pole circuit corner tension-resistant fittings, not only versatility is strong, operation method is simple, light and flexible, and greatly alleviated the workload of live operator on the tower, improved operating efficiency.

Finally, it is noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Those of ordinary skill in the art may make other modifications or equivalent replacements to the technical solution of the present invention, as long as they do not depart from the spirit and spirit of the technical solution of the present invention. All should be included in the scope of the claims of the present invention.

Claims (8)

1. change the instrument of ground electrode circuit corner strain hardware fitting for one kind, it is characterized in that: comprise front card, rear card and thread-tightening lead screw, before described, card is set to two links, described link is set to " U " shape, described link one end is fixedly connected with cross-arm, described rear card one end is connected with triangle yoke plate, described Wire tensioning screw is arranged between link and rear card, described Wire tensioning screw comprises thrust bearing, handle, leading screw, ratchet casing tube and bearing pedestal, described thrust bearing is fixedly connected with the link other end, described handle is arranged in the middle part of leading screw, described ratchet casing tube to be arranged between leading screw and bearing pedestal and to be socketed in outside described leading screw, described ratchet casing tube is fixedly connected with bearing pedestal, described bearing pedestal is fixedly connected with the rear card other end, described link, rear card and thread-tightening lead screw all adopt high-strength steel material to make.

2. a kind of instrument changing ground electrode circuit corner strain hardware fitting as claimed in claim 1, is characterized in that: block after described rear card is set to yoke plate, and after described yoke plate, cartoon is crossed right angle link plate and is fixedly connected with triangle yoke plate.

3. a kind of instrument changing ground electrode circuit corner strain hardware fitting as claimed in claim 1, is characterized in that: block after described rear card is set to crotch, after described crotch, card one end is fixedly connected with bearing pedestal, and the other end is flexibly connected with triangle yoke plate.

4. a kind of instrument changing ground electrode circuit corner strain hardware fitting as claimed in claim 2, it is characterized in that: after described yoke plate, card both sides are respectively arranged with for first installing hole fixing with bearing pedestal, after described yoke plate card middle part be provided with for right angle link plate and fixing the second installing hole of triangle yoke plate.

5. a kind of instrument changing ground electrode circuit corner strain hardware fitting as claimed in claim 3, is characterized in that: after described crotch, card one end is provided with for three installing hole fixing with bearing pedestal.

6. a kind of instrument changing ground electrode circuit corner strain hardware fitting as claimed in claim 1, it is characterized in that: described high-strength steel is according to weight percent meter, comprise following constituent: C=0.12 ~ 0.20%, Si=1.60 ~ 1.85%, Mn=0.85 ~ 2.3%, Cr=1.85 ~ 3.12%, Ni=0.72 ~ 1.86%, Mo=0.32 ~ 0.86%, Ti=0.08 ~ 0.12%, Nb=0.04 ~ 0.08%, V=0.12 ~ 0.19%, B=0.001 ~ 0.0022%, Tm=3.6 ~ 4.8%, S=0.002 ~ 0.010%, all the other are iron and inevitable impurity.

7. a kind of instrument changing ground electrode circuit corner strain hardware fitting as described in claim 1 or 6, is characterized in that: the preparation method of described high-strength steel comprises the following steps:

(1) weigh various raw material, and fragmentation and the grinding of 30 ~ 40min are carried out to block stock;

(2) all raw materials are mixed, stir 30 ~ 45min in forced mixer, obtain mixed material;

(3) step (2) described mixed material is placed in smelting furnace and smelts 35 ~ 50min in 1800 ~ 2400 DEG C, obtain molten steel;

(4) pour in mold by step (3) gained molten steel, forge 12 ~ 14 passages at 860 ~ 910 DEG C, cooling rate is water-cooled cooling to 350 ~ 450 DEG C of 0.5 ~ 1 DEG C/s, then Air flow is to normal temperature, obtains steel ingot;

(5) step (4) gained steel ingot is carried out Quenching Treatment: by Heating Steel Ingots to 800 ~ 900 DEG C, insulation 3 ~ 5h, is placed in air, water or oil and carries out being cooled to room temperature;

(6) step (5) gained steel ingot is carried out temper: steel ingot Quenching Treatment crossed is heated to 550 ~ 680 DEG C again, insulation 2 ~ 3h, is placed in air, water or oil and carries out being cooled to room temperature.

8. the method changing ground electrode circuit corner strain hardware fitting as claimed in claim 1, is characterized in that: comprise the following steps:

1) front card one end is fixedly connected on the construction hole place of cross-arm, the other end is fixedly connected with thrust bearing, then is fixedly connected with rear card one end by bearing pedestal, and the rear card other end is connected with triangle yoke plate;

2) suitably tighten up Wire tensioning screw by handle and guarantee instrument front and back end uniform force and Wire tensioning screw stroke suitable;

3) tighten up Wire tensioning screw and make that circuit corner strain hardware fitting is stressed to be transferred on replacing instrument.