A construction method for an urban rail transit return flow system

Abstract

The present application discloses a construction method of an urban rail transit equalizing return system, which belongs to the field of rail transit technology and includes the following steps: drilling holes at set positions of contact rails; installing expansion nails; installing contact rails; fixing copper bars on the contact rails with clamps so that the front of the copper bars abuts against the position where the contact rails are coated with flux; performing low-temperature soldering; removing the clamps, applying sealant on the surface of the copper bars, and applying anti-rust paint on the polished part of the contact rails; performing flaw detection on the contact rails; laying and fixing equalizing return cables, connecting one end of the equalizing box to the contact rails, and the other end to the potential limiting device of the contact rails of the substation: connecting one end of the return box to the contact rails, and the other end to the negative pole cabinet of the substation, thereby completing the construction of the equalizing return system. The present application solves the problems of low reliability and poor safety of the equalizing return system after construction in the prior art. The present application improves the reliability of the equalizing return system after construction.

Description

Technical Field

[0001] The present application belongs to the field of rail transit technology, and specifically relates to a construction method for a uniform return flow system of urban rail transit. Background Art

[0002] The DC power supply traction system of urban rail transit consists of rectifier units, contact rails, contact rail access cables, rails, return cables, rail potential limiting devices, one-way conduction devices, drain cabinets, roadbeds, tunnel structure steel bars and other links. Each part complements each other and together constitutes the power supply and return path of the traction current, ensuring that the traction power supply can smoothly return from the positive pole of the power supply to the negative pole of the power supply under normal conditions and fault conditions. However, the current return system in the DC power supply traction system does not have a relatively complete construction process, and most of them are temporary construction processes compiled on site. Therefore, the return system has problems such as low reliability and poor safety after construction. Summary of the invention

[0003] The embodiment of the present application solves the problems of low reliability and poor safety of the equal return system after construction in the prior art by providing a construction method of the equal return system of urban rail transit.

[0004] In order to achieve the above object, an embodiment of the present invention provides a construction method of an urban rail transit equalization return system, comprising the following steps:

[0005] Determine the installation position of the return cable according to the position of the pre-buried pipe in the platform and make a mark;

[0006] Drilling holes at set positions of the contact rail;

[0007] Measuring the diameter of the drilled hole, and then installing the expansion nails on the contact rail;

[0008] Installing the contact rail;

[0009] Clean the position of the contact rail that needs to be brazed and apply flux to the position; stick a flame retardant strip on the back of the copper busbar and apply flux on the front of the copper busbar;

[0010] Fixing the copper busbar on the contact rail by using a clamp so that the front surface of the copper busbar abuts against the position where the soldering flux is applied on the contact rail;

[0011] Aim a flamethrower at a side wall of the contact rail away from the copper busbar, and perform low-temperature brazing;

[0012] After welding, remove the fixture, apply sealant on the surface of the copper bar, and apply anti-rust paint on the polished part of the contact rail;

[0013] The copper busbar and the contact rail are further fixed by expansion nails;

[0014] Performing flaw detection on the contact rail;

[0015] Lay and fix the return current sharing cable, connect one end of the current sharing box to the contact rail, and the other end to the substation contact rail potential limiting device: connect one end of the return box to the contact rail, and the other end to the substation negative pole cabinet, thereby completing the construction of the return current sharing system.

[0016] In a possible implementation, the auxiliary punching dies are used to drill holes, and two punching dies are first installed on both sides of the contact rail through the electromagnets thereon. After the positions of the punching dies are adjusted, the punching dies and the contact rail are further fixed by a clamping mechanism;

[0017] The positioning holes of the punching die are used for punching, and water is injected into the positioning holes through the water inlet hole. The water flows to the contact rail and the drill bit through the channel between the water inlet hole and the positioning hole, and the water cools the contact rail and the drill bit.

[0018] In a possible implementation, when the punching die and the contact rail are further fixed by a clamping mechanism, the U-shaped clamp of the clamping mechanism is firstly mounted on the set position of the punching die, and then the position of the movable sleeve of the clamping mechanism in the mounting hole on the U-shaped clamp is adjusted so that the end of the movable sleeve is close to the punching die, and then the movable sleeve is rotated so that the clamping rod of the movable sleeve is clamped in the clamping groove in the mounting hole, and then the stud in the movable sleeve is rotated so that the end of the stud abuts against the punching die, thereby completing the fixation of the punching die and the contact rail.

[0019] In a possible implementation, a diameter measuring device is used to measure the diameter of the borehole on the contact rail, and then the borehole is chamfered, and the surfaces of the contact rail on both sides of the borehole are polished smooth, and then the copper tube sleeve of the expansion nail is placed into the borehole;

[0020] Insert the mandrel into the inner shaft of the copper sleeve, turn the mandrel into the head of the hydraulic riveting machine, turn on the hydraulic riveting machine until the mandrel is completely passed through and the head of the hydraulic riveting machine falls off, press the pedal of the hydraulic riveting machine to release the pressure and the installation of the expansion nail is completed.

[0021] In a possible implementation, when installing the contact rail, the claw bolts of the insulating bracket are removed, the contact rail is lifted and pushed onto the claw, and the removed claw is fixed synchronously with the contact rail; after the fixing is completed, the contact rail is aligned up and down and left and right using a jack;

[0022] When installing the middle joint of the contact rail, evenly apply conductive paste on the contact surface of the middle joint and align it with the hole, insert the Hake bolts in sequence and place the rivets and install them; after installation, check the vertical and horizontal errors and the contact rail gap errors;

[0023] When installing the electrical connection plate, punch holes in the electrical connection plate at the electrical point position of the contact rail cable, and evenly apply conductive paste on the contact surface of the electrical connection plate. After the electrical connection plate is tightly fitted to the contact rail, install the Hake bolts in place.

[0024] In a possible implementation, after the contact rail is installed, the values ​​of the limit and the height of the contact rail are detected, and if they exceed the set requirements, the contact rail is adjusted.

[0025] In a possible implementation, after the contact rail is installed, it is determined whether the construction area is humid. If it is humid, an outdoor distribution box is set up during electrical operations, and a dehumidification device is provided in the outdoor distribution box.

[0026] In a possible implementation, the low-temperature brazing time is 20-40 minutes, and when the temperature at the brazing point drops below 100° C., the clamp is removed.

[0027] In one possible implementation, before applying flux, three limit pins of equal length are set on the application brush so that the application brush always maintains a set distance from the contact rail and copper busbar. When applying flux, the flux is placed on the application brush. During the application process, excess flux is taken away by the baffle at the rear of the application brush.

[0028] In a possible implementation, the copper busbar is fixed in front of the contact rail using a clamp, a positioning plate is placed at the position where the copper busbar is set on the contact rail, the positioning plate is magnetic, and the copper busbar is positioned using the positioning plate. After the copper busbar is initially fixed to the contact rail using a clamp, the position of the clamp is fine-tuned, and then the copper busbar is fixed to the contact rail using the clamp.

[0029] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0030] The embodiment of the present invention provides a construction method for an urban rail transit equal return system. The method can well improve the reliability of the equal return system after construction by reasonably setting the construction sequence and construction steps of components such as contact rails, copper bars, and equal return cables. The method improves the safety of the equal return system. The method is simple, fast, safe, and highly practical, and is easy to operate and has high construction efficiency.

[0031] When drilling with the auxiliary punching mold, preliminary positioning and installation are performed through magnets, which can save the inconvenience caused by manual fixation, thereby improving the efficiency of the mold when in use. Cooling the contact rail and the drill bit can ensure the smooth drilling and improve the quality of the drilling. Three equal-length limit pins are set on the smear brush to enable the flux to be evenly applied to the contact rail and the copper busbar, ensuring that the flux achieves the best fluxing effect, while avoiding the problem of insufficient flux affecting the fluxing effect, or excessive flux wasting flux. The positioning plate can improve the efficiency of the clamp when fixing the copper busbar, while ensuring the accuracy of its position after the copper busbar is fixed. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A flowchart of a construction method for an urban rail transit equalization return system provided in an embodiment of the present invention.

[0034] Figure 2 A schematic structural diagram of an auxiliary punching die provided in an embodiment of the present invention.

[0035] Figure 3 for Figure 2 AA section view.

[0036] Figure 4 A schematic structural diagram of a punching die provided in an embodiment of the present invention.

[0037] Figure numerals: 1-clamping mechanism; 2-punching mold; 3-positioning hole; 4-electromagnet; 5-water inlet hole; 6-water inlet channel; 7-U-shaped clamp; 71-clamping groove; 72-mounting hole; 8-rotational force application part; 81-movable sleeve; 82-clamping rod; 83-stud; 84-turn handle; 9-cavity; 10-hole mold; 11-contact rail. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the description of the embodiments of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present invention. The terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

[0040] like Figures 1 to 4 As shown, the urban rail transit equal return system construction method provided by the embodiment of the present invention includes the following steps:

[0041] Step 1: Measure and locate, determine the installation position of the return cable according to the position of the pre-buried pipe in the platform, and make a mark;

[0042] Determine the installation location of the traction cable according to the mileage and interval marked on the blueprint, and make clear marks and records.

[0043] Step 2: Drilling holes in the contact rail, using an auxiliary punching die to drill holes at set positions of the contact rail;

[0044] In this embodiment, the auxiliary punching die 2 is used to drill holes. First, the two punching dies 2 are installed on both sides of the contact rail 11 through the electromagnets 4 thereon. After adjusting the positions of the punching dies 2, the punching dies 2 and the contact rail 11 are further fixed by the clamping mechanism 1.

[0045] The positioning hole 3 of the punching mold 2 is used for punching, and water is injected into the positioning hole 3 through the water inlet hole 5. The water flows to the contact rail 11 and the drill bit through the channel between the water inlet hole 5 and the positioning hole 3, and the water cools the contact rail 11 and the drill bit.

[0046] By using magnets for preliminary positioning and installation, the inconvenience caused by manual fixing can be eliminated, thereby improving the efficiency of the mold when in use. Cooling the contact rail 11 and the drill bit can ensure smooth drilling and improve the quality of the drilling.

[0047] When the punching die 2 and the contact rail 11 are further fixed by the clamping mechanism 1, the U-shaped clamp 7 of the clamping mechanism 1 is first mounted on the set position of the punching die 2, and then the position of the movable sleeve 81 of the clamping mechanism 1 in the mounting hole 72 on the U-shaped clamp 7 is adjusted so that the end of the movable sleeve 81 is close to the punching die 2, and then the movable sleeve 81 is rotated so that the clamping rod 82 of the movable sleeve 81 is clamped in the clamping groove 71 in the mounting hole 72, and then the stud 83 in the movable sleeve 81 is rotated so that the end of the stud 83 abuts against the punching die 2, thereby completing the fixation of the punching die 2 and the contact rail 11.

[0048] The clamping mechanism 1 of the present invention first moves a long distance through the movable sleeve 81, and then fixes the punching mold 2 by rotating the stud 83, thereby avoiding the problem of excessive moving distance when only fixing by rotating the stud 83, thereby further improving the efficiency of the device when in use.

[0049] The auxiliary punching die 2 of the present invention comprises a clamping mechanism 1 and two punching dies 2 of the same structure. The cross section of the punching die 2 is a trapezoidal structure adapted to the side wall structure of the contact rail 11, and a positioning hole 3 is provided on the punching die 2, and an electromagnet 4 is provided on both sides of the positioning hole 3 of the punching die 2. The two punching dies 2 are arranged on both sides of the contact rail 11, and the clamping mechanism 1 makes the punching die 2 abut against the contact rail 11. The punching die 2 is provided with a water inlet hole 5, and the water inlet hole 5 is connected with the positioning hole 3 through a water inlet channel 6. The clamping mechanism 1 comprises a U-shaped clamp 7, and a rotating force applying part 8 symmetrically arranged on both sides of the U-shaped clamp 7. The rotating force applying part 8 comprises a movable sleeve 81, a clamping rod 82, a stud 83, and a rotating handle 84. The clamping rod 82 is vertically mounted on the outer wall of the movable sleeve 81, and the stud 83 is coaxially arranged in the movable sleeve 81. The rear end of the stud 83 extends out of the movable sleeve 81 and is connected to the turning handle 84. The front end of the inner wall of the movable sleeve 81 is provided with an internal thread matched with the stud 83. The movable sleeve 81 is installed in the mounting hole 72 of the side wall of the U-shaped clip 7. One side of the mounting hole 72 is provided with a sector-shaped columnar cavity 9 for the clamping rod 82 to move. The cavity 9 is provided with a plurality of clamping grooves 71 for clamping the clamping rod 82 at intervals in the extending direction of the movable sleeve 81. The movable sleeve 81 can move along its axial direction in the mounting hole 72. When the movable sleeve 81 moves, the clamping rod 82 moves in the cavity 9. The cavity 9 is a fan-shaped columnar structure, so the movable sleeve 81 can also rotate when it moves. When the movable sleeve 81 rotates and the clamping rod 82 is clamped in the clamping groove 71, the movable sleeve 81 cannot move axially. When drilling the positioning hole rail, at the waist of the rail, at the position where the positioning is completed, the rail is drilled with a ф19mm hollow drill bit, and the error of the drilling hole diameter is required to be less than 1mm; use an alloy drill bit to drill a hole with a diameter of ф19mm. Note that the position with the letter size on the rail cannot be drilled. After the hole is opened, it is required to use a cone to chamfer the two sides of the hole by 1×45° to remove burrs and tiny cracks caused by drilling. The distance between the second hole and the first hole is 210mm, the distance between the edge of the drilled hole and the edge of the exothermic welding weld on the rail is required to be 210mm; the distance between the drilled hole position and the rail joint position is required to be 1m.

[0050] After drilling is completed, expansion nails are installed to prevent rust on the inner wall of the hole. After drilling, the hole is treated with cold expansion using a riveting machine.

[0051] Using a diameter measuring device to measure the diameter of the drilled hole, and then installing the expansion nails on the contact rail;

[0052] In this embodiment, after measuring the diameter of the hole drilled on the contact rail with the diameter measuring device, the hole is chamfered, and the holes on both sides are chamfered by 1*45° with a taper. After the surfaces of the contact rail on both sides of the hole are polished smooth with a grinder, the hole edges are cleaned with a taper. After the cleaning is completed, the expansion nail can be installed. The copper tube sleeve of the expansion nail is placed in the drill hole;

[0053] Insert the mandrel into the inner shaft of the copper sleeve, and use the tail end of the diameter measuring instrument to turn the mandrel into the head of the hydraulic riveting machine. Note that the mandrel must be completely turned into the head of the hydraulic riveting machine. Turn on the hydraulic riveting machine until the mandrel is completely passed through and the head of the hydraulic riveting machine falls off. Press the pedal of the hydraulic riveting machine to release the pressure and the installation of the expansion nail is completed.

[0054] Step 3: Installation of the contact rail: installing the contact rail;

[0055] In this embodiment, when installing the contact rail, the claw bolts of the insulating bracket are removed, the contact rail is lifted and pushed onto the claw, and the removed claw is fixed synchronously with the contact rail; after the fixing is completed, the contact rail is aligned up and down and left and right using a jack;

[0056] When installing the middle joint of the contact rail, evenly apply conductive paste on the contact surface of the middle joint and align it with the hole, insert the Hake bolts in turn and place the rivets, and use the Hake electric hydraulic ring groove riveter to install it in place; after installation, use the contact rail detection ruler to detect the vertical and horizontal errors, and use the feeler gauge to detect the error of the contact rail seam;

[0057] When installing the electrical connection plate, punch holes in the electrical connection plate at the electrical point position of the contact rail cable, and evenly apply conductive paste on the contact surface of the electrical connection plate. After the electrical connection plate fits tightly against the contact rail, use the Hake electric hydraulic ring groove rivet machine to install the Hake bolts in place.

[0058] In this embodiment, after the contact rail is installed, the contact rail detection device is used to detect the values ​​of the limit and the height of the contact rail. If they exceed the set requirements, the contact rail is adjusted.

[0059] In this embodiment, after the contact rail is installed, it is determined whether the construction area is humid. If it is humid, an outdoor distribution box is set up during electrical operations, and a dehumidification device is provided in the outdoor distribution box.

[0060] Step 4: Installation of the copper busbar, clean the position of the contact rail that needs to be brazed, and apply flux to the position; stick a flame retardant strip on the back of the copper busbar, and apply flux on the front of the copper busbar.

[0061] Before applying the flux, set three equal-length limit pins on the smear brush so that the smear brush always maintains a set distance from the contact rail and copper busbar. When applying the flux, place the flux on the smear brush. During the application process, the excess flux is taken away by the baffle at the rear of the smear brush. Setting three equal-length limit pins on the smear brush can make the flux evenly applied to the contact rail and copper busbar, ensuring that the flux achieves the best fluxing effect, while avoiding the problem of insufficient flux affecting the fluxing effect, or excessive flux wasting flux.

[0062] Use an angle grinder to remove the rust on the rail where the copper bar needs to be brazed, and use a clean brush to clean the polished surface. Stick a flame retardant strip on the back of the copper bar and cut it off with a utility knife.

[0063] The copper busbar is fixed on the contact rail by using a clamp so that the front surface of the copper busbar abuts against the position of the contact rail where the soldering flux is applied.

[0064] Before the copper bar is fixed to the contact rail by a clamp, a positioning plate is placed at the position where the copper bar is set on the contact rail. The positioning plate has magnetism, and the copper bar is positioned by the positioning plate. After the copper bar is initially fixed to the contact rail by a clamp, the position of the clamp is fine-tuned, and then the copper bar is fixed to the contact rail by the clamp. The positioning plate can improve the efficiency of the clamp when fixing the copper bar, and at the same time ensure the accuracy of the position of the copper bar after it is fixed.

[0065] Aim a flamethrower at a side wall of the contact rail away from the copper busbar, and perform low-temperature brazing;

[0066] After welding, remove the fixture, apply sealant on the surface of the copper bar, and apply anti-rust paint on the polished part of the contact rail;

[0067] In this embodiment, the low-temperature brazing time is 20-40 minutes, and when the temperature at the brazing point drops below 100° C., the clamp is removed.

[0068] The copper busbar and the contact rail are further fixed by expansion nails through a hydraulic press;

[0069] Place the rail drilling machine on the rail, with the drill bit on the side of the rail without the copper bar, use a three-edged chamfering cutter to chamfer both sides of the hole, put the expansion nail in the hole, with the big head of the expansion nail on the side with the copper bar, put the pull pin into the expansion nail hole, with the side with the hexagonal head at the big end of the expansion nail. Use a wrench to screw the pull pin into the threaded hole of the hydraulic press head and tighten it.

[0070] Move the handle of the hydraulic press up and down to pull out the pull pin. After the pull pin is fully pulled out, the expansion nail will form a flange on the back of the rail and fix it on the rail.

[0071] Performing flaw detection on the contact rail by moving the rail flaw detection device;

[0072] The contact rail detection device adopts "A Mobile Contact Rail Detection Device" with publication number CN207730152U. The device of this patent can realize continuous monitoring of the contact rail, improve work efficiency and realize full-process monitoring of the contact rail. It is easy to implement, easy to control and low in cost.

[0073] Step 5: Installation of the equalizing return cable and the equalizing return box, laying and fixing the equalizing return cable, connecting one end of the equalizing box to the contact rail, and the other end to the substation contact rail potential limiting device: connecting one end of the return box to the contact rail, and the other end to the substation negative pole cabinet, thereby completing the construction of the equalizing return system.

[0074] One end of the current equalizing box is connected to the rail, and the other end is connected to the substation rail potential limiter: one end of the return box is connected to the rail, and the other end is connected to the substation negative cabinet. The lead-in line of the equalizing and return boxes, that is, the 150mm cross-section cable from the rail to the box wiring copper bar, should be connected to the designated rail rail, and the connection position should be constructed according to the position given in the cable laying diagram. The lead-out line of the current equalizing box, that is, the 400mm cross-section cable from the current equalizing box to the rail potential limiter, should be laid and installed.

[0075] The present invention provides a construction method for an urban rail transit equalizing return system. The method can well improve the reliability of the equalizing return system after construction by reasonably setting the construction sequence and construction steps of components such as contact rails, copper bars, and equalizing return cables. The method improves the safety of the equalizing return system. The method is simple, fast, safe, and highly practical, and is easy to operate with high construction efficiency.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A construction method for an urban rail transit return system, characterized in that: The following steps are involved: Determine the installation position of the return cable according to the position of the pre-buried pipe in the platform and make a mark; Drilling holes at set positions of the contact rail: drilling holes using an auxiliary punching die; The auxiliary punching die comprises a clamping mechanism and two punching dies with the same structure; the cross section of the punching die is a trapezoidal structure adapted to the side wall structure of the contact rail, a positioning hole is arranged on the punching die, and electromagnets are arranged on both sides of the positioning hole; the two punching dies are arranged on both sides of the contact rail, and the clamping mechanism makes the punching die abut against the contact rail; the punching die is provided with a water inlet hole, and the water inlet hole is connected with the positioning hole through the water inlet channel; the clamping mechanism comprises a U-shaped clamp and a rotating force applying part symmetrically arranged on both sides of the U-shaped clamp; the rotating force applying part comprises a movable sleeve, a clamping rod, a stud, and a rotating handle; the clamping rod is vertically installed on the outer wall of the movable sleeve, and the stud is coaxially arranged on In the movable sleeve, the rear end of the stud extends out of the movable sleeve and is connected to the turning handle. The front end of the inner wall of the movable sleeve is provided with an internal thread matched with the stud; the movable sleeve is installed in the mounting hole of the side wall of the U-shaped clamp, and one side of the mounting hole is provided with a fan-shaped columnar cavity for the movement of the clamping rod; the cavity is provided with a plurality of clamping grooves for clamping the clamping rod at intervals in the extension direction of the movable sleeve; the movable sleeve can move along its axial direction in the mounting hole, and when the movable sleeve moves, the clamping rod moves in the cavity. The cavity is a fan-shaped columnar structure, so the movable sleeve can also rotate when it moves. When the movable sleeve rotates and the clamping rod is clamped in the clamping groove, the movable sleeve cannot move axially; When drilling holes using the auxiliary punching die, first install the two punching dies on both sides of the contact rail through the electromagnets thereon, and after adjusting the positions of the punching dies, further fix the punching dies and the contact rail through the clamping mechanism; The positioning holes of the punching die are used for punching, water is injected into the positioning holes through the water inlet holes, the water flows to the contact rail and the drill bit through the channel between the water inlet holes and the positioning holes, and the water cools the contact rail and the drill bit; When the punching die and the contact rail are further fixed by the clamping mechanism, the U-shaped clamp of the clamping mechanism is firstly sleeved on the set position of the punching die, and then the position of the movable sleeve of the clamping mechanism in the mounting hole on the U-shaped clamp is adjusted so that the end of the movable sleeve is close to the punching die, and then the movable sleeve is rotated so that the clamping rod of the movable sleeve is clamped in the clamping groove in the mounting hole, and then the stud in the movable sleeve is rotated so that the end of the stud is abutted against the punching die, thereby completing the fixing of the punching die and the contact rail; Measuring the diameter of the drilled hole, and then installing the expansion nails on the contact rail; Installing the contact rail; Cleaning the position of the contact rail to be brazed and applying flux to the position; A flame retardant strip is attached to the back of the copper busbar, and flux is applied to the front of the copper busbar; Fixing the copper busbar on the contact rail by using a clamp so that the front surface of the copper busbar abuts against the position where the soldering flux is applied on the contact rail; Aim a flamethrower at a side wall of the contact rail away from the copper busbar, and perform low-temperature brazing; After welding, remove the fixture, apply sealant on the surface of the copper bar, and apply anti-rust paint on the polished part of the contact rail; The copper busbar and the contact rail are further fixed by expansion nails; Performing flaw detection on the contact rail; Lay and fix the return current sharing cable, connect one end of the current sharing box to the contact rail, and the other end to the substation contact rail potential limiting device: connect one end of the return box to the contact rail, and the other end to the substation negative pole cabinet, thereby completing the construction of the return current sharing system.

2. The construction method of the urban rail transit return system according to claim 1 is characterized in that: The diameter of the hole drilled on the contact rail is measured by a diameter measuring device, and then the hole is chamfered. After the surfaces of the contact rail on both sides of the hole are polished smooth, the copper tube sleeve of the expansion nail is placed into the hole; Insert the mandrel into the inner shaft of the copper sleeve, turn the mandrel into the head of the hydraulic riveting machine, turn on the hydraulic riveting machine until the mandrel is completely passed through and the head of the hydraulic riveting machine falls off, press the pedal of the hydraulic riveting machine to release the pressure and the installation of the expansion nail is completed.

3. The construction method of the urban rail transit return system according to claim 1 is characterized in that: When installing the contact rail, remove the claw bolts of the insulating bracket, lift the contact rail and push it onto the claw, and fix the removed claw and the contact rail synchronously; after fixing, use a jack to align the contact rail up and down and left and right; When installing the middle joint of the contact rail, evenly apply conductive paste on the contact surface of the middle joint and align it with the hole, insert the Hake bolts in sequence and place the rivets and install them; after installation, check the vertical and horizontal errors and the contact rail gap errors; When installing the electrical connection plate, punch holes in the electrical connection plate at the electrical point position of the contact rail cable, and evenly apply conductive paste on the contact surface of the electrical connection plate. After the electrical connection plate is tightly fitted to the contact rail, install the Hake bolts in place.

4. The construction method of the urban rail transit return system according to claim 1 is characterized in that: After the contact rail is installed, the limit and guide height values ​​of the contact rail are tested. If they exceed the set requirements, the contact rail is adjusted.

5. The construction method of the urban rail transit return system according to claim 1 is characterized in that: After the contact rail is installed, determine whether the construction area is humid. If it is humid, set up an outdoor distribution box during electrical operations, and the outdoor distribution box is equipped with a dehumidification device.

6. The construction method of the urban rail transit return system according to claim 1 is characterized in that: The low-temperature brazing time is 20-40 minutes. When the temperature at the brazing point drops below 100° C., the clamp is removed.

7. The construction method of the urban rail transit return system according to claim 1 is characterized in that: Before applying flux, set three limit pins of equal length on the application brush so that the application brush always maintains a set distance from the contact rail and copper busbar. When applying flux, place the flux on the application brush. During the application process, excess flux is taken away by the baffle at the rear of the application brush.

8. The construction method of the urban rail transit return system according to claim 1 is characterized in that: The copper busbar is fixed in front of the contact rail by using a clamp, and a positioning plate is placed at the position where the copper busbar is set on the contact rail. The positioning plate is magnetic, and the copper busbar is positioned by using the positioning plate. After the copper busbar is initially fixed on the contact rail by using a clamp, the position of the clamp is fine-tuned, and then the copper busbar is fixed on the contact rail by using the clamp.

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