Who has the welding operation method of thermite welding?

I. Compilation Basis 1

II. Project Overview 1

Iii. Labor Distribution 1

Four, mechanical equipment 2

Five, aluminothermic welding process flow chart and welding sequence figure 2

Technical requirements for construction working environment and use of construction equipment and products 3

Seven. Construction operation step 3

Eight, welding joint straightness and surface quality requirements 9

Nine, flaw detection 10

X. welding record 10

XI。 Safety and quality measures 1 1

Xii. Operating procedures for thermite welding 12

Xiii. Safety operation procedures for thermite welding 12

Special scheme for welding construction of turnout in newly-built Ganshao railway

I. Basis for compilation

1. 1 According to People's Republic of China (PRC) railway industry standard TB/T 1632.3-2005 and Technical Guide for Track Construction of Passenger-Freight Railway (TZ20 1-2008).

1.2 Design drawings for jointless track of newly-built Gan-Shao railway project;

1.3 construction contract and the effective constituent documents of the contract;

1.4 rail welding test parameters;

Second, the project overview

The newly-built Gan-Shao (Ganzhou-Shaoguan) railway is located in Jiangxi and Guangdong provinces in the south of China, in the south of Jiangxi Province and in the north of Guangdong Province, connecting the two main north-south railway trunk lines in China-the Beijing-Guangzhou line and the Beijing-Kowloon line. The line leads from Nankang Station of Beijing-Kowloon Railway, passes through Nankang City and Dayu County of Jiangxi Province, Nanxiong City, Shixing City and Renhua City of Guangdong Province, and connects to Shaoguan East Station of Beijing-Guangzhou Railway.

There are *** 16 stations on the whole line, including 4 new stations 14 new railway stations 1 4 reconstructed stations 1 3 groups, namely, Shaoguan East Station and Turnouts 1 13.

Third, labor distribution.

According to the turnout welding construction and quantity, the turnout welding quantity of the whole station is 1000.

According to the track-laying situation of the station and the construction progress plan at this stage, the aluminothermic welding construction team of the turnout rail of Lashiba Station with 1 group of ***24 professionals will be deployed for construction. Four of them are professional welders, and the rest are laborers.

According to the past, it takes 30 minutes to complete the contact welding of 1 switch head, during which rail alignment, rail grinding, switch welding, welding head grinding and finishing operations are required.

Therefore, the project department decided to adopt assembly line operation for turnout welding after research, and the turnout welding was divided into three groups. One group is rail alignment and grinding, one group is turnout welding and grinding, and the third group is fastener fitting installation and line direction adjustment.

Fourth, machinery and equipment.

According to the welding quantity and construction schedule of Lashiba Station, prepare professional machinery and equipment for thermite welding of rails. See attached table for main tools:

Five, aluminothermic welding process flow chart and welding sequence diagram

5. 1 aluminothermic welding process flow chart

According to the design, the turnout welding adopts "welding construction after turnout laying". Inside the turnout, aluminothermic welding is adopted, and the welding materials and technology of Lajtek company in France are adopted.

Process flow chart of thermite welding

5.2 welding sequence diagram

Turnout welding sequence diagram

According to the welding sequence shown in the above figure, the sequence is 1, 2, 3, 4, 5 and 6. Details are as follows:

(1) The connection between the frog rail row and the guide rail shall be straight and then bent;

(2) In the heel of guide rail and switch rail, switch rail should be straight before bending.

(3) basic rail welding, straight strand first, then bent strand;

④ Welding sequence of rails before and after turnout: before turnout and after turnout; Straight strands first, then bent strands.

The temperature of welded locking rail of turnout rail provided by the design is 32 5℃

VI. Construction environment and technical requirements for the use of construction equipment and products

1, when welding in cold, windy and rainy days, tents must be set up, and heat preservation measures should be taken in the welding area. When the temperature is below 0℃ and it is windy and rainy, welding is prohibited. When the temperature difference changes greatly, the rail puller must be used for welding under the condition of ensuring the stability of the rail gap size.

2, thermite flux should be sealed packaging, to have a dry storage environment, to have a packaging mark, easy to identify the product model, production date.

3. The sand mold is prefabricated and coincides with the section of the rail to be welded; There is a mark on the package, which is convenient to identify the product type and production date; Do not get wet, damaged or cracked.

4. The crucible shall not be affected with damp, damaged or broken before use. Equipped with crucible cover to limit splashing of molten steel; The fusible plug at the bottom of the crucible is used to control the time of molten steel flow and must be kept in good condition.

5, oxygen and propane used in winter take heat preservation measures to ensure the normal pressure of gas.

VII. Construction Steps

7. 1 construction preparation

7. 1. 1 Check the construction site. Before welding, designate a special person to check according to the welding project list to prevent leakage and affect the construction.

7. 1.2 Check the construction machines and tools and try them out to ensure that the equipment is in good condition before welding 100%. Use soapy water to detect oxygen cylinders, gas cylinders and other systems. If there is air leakage, it cannot be used.

7. 1.3 Check the straightness and surface condition of the track. Check the end of the track for cracks, inclination or other defects. When there is a low joint at the end of the rail, the low joint must be sawed off. Corners more than 2mm deep must be sawed off.

7. 1.4 Check the size and position of the rail gap and the dislocation of the joint. The weld shall not fall on the sleeper, and the position of the rail gap shall be greater than 100mm from the edge of the sleeper, so as to ensure that the misalignment of the left and right rail joints meets the requirement of less than 100mm during tensioning.

7. 1.5 Measure the track temperature. Measure the rail temperature at the backlight side of the rail, and do not weld when the rail temperature is lower than 0℃.

7. 1.6 Fasteners must be installed within 50m on both sides of welded rails in strict accordance with regulations, so as to ensure that the gaps between rails cannot move during welding, which will affect the welding quality and even lead to molten steel leakage.

7.2 rail end drying

7.2. 1 Before the rail end is derusted and decontaminated, both sides of the rail weld can be baked with a preheating gun within the range of 1 m, so as to fully eliminate the moisture and oil stain on the rail surface.

7.3 Derusting and decontamination of rail end

7.3. 1 Use an angular grinder with a steel wire brush to polish and clean the rust on the welded rail end, sides, rail head and rail bottom, with the range of100-150 mm. Pay special attention to the cleaning of rail bottom, and the rail end is not vertical below1mm.

7.4 alignment

7.4. 1 Rail gap adjustment: measured at both sides of rail head and rail bottom, the rail gap shall meet 25±2mm under the same conditions. Keep the gap constant during welding. From the rail alignment until the rail temperature drops below 300℃ after welding, or 30 minutes after pouring, it is forbidden to loosen fasteners, pull wires, pull rails and smash cars within 50m at both ends of the weld.

7.4.2 Alignment: overlap the midpoint of the 1m ruler with the midpoint of the welding gap, and adjust the height of the rail frame with a steel wedge so that the gap between the rail top surface and the ruler at 0.5m on both sides of the weld is about1.6mm..

7.4.3 Horizontal alignment: use 1m straightedge to cling to rail head and rail waist respectively, and use steel straightedge to cling to rail foot. Generally, the three places must be closely attached to form a horizontal alignment. It is necessary to ensure that the active surface side of the joint is horizontally aligned, and the longitudinal inner side of the track is required to be straight. Use a ruler of 1m to measure the flatness of two rails at the same time, and the dislocation shall not be greater than 0.2 mm ..

7.4.4 Adjust the height of the track first, then adjust the level, and finally adjust the unequal inclination.

7.5 sand mold installation

7.5. 1 Check that the sand mold should be free from moisture, cracks and deformation, and all parts should be complete and in good condition. Cracked or wet sand molds cannot be used;

7.5.2 The pouring hole of sand mold should take a short rest to prevent sand particles from falling off at high temperature;

7.5.3 Rub the contact surface between the sand mold and the rail, so that the joint between the sand mold and the rail is closely attached;

7.5.4 If the contact surface between the sand mold and the rail is not well matched, there will be serious consequences of breakout;

7.5.5 The bottom die must be centered and close to the track.

7.5.6 The sand mold pouring hole should be symmetrical with the left and right rail angles to ensure that the rail bottoms on both sides are evenly heated;

7.5.7 The center of the sand mold is consistent with the center of the rail gap, the sand mold is perpendicular to the rail, and the two sand molds should be aligned.

7.5.8 When tightening the fixture, it shall be completed by one person and evenly clamped.

7.5.9 Try to put the shunt plug so that the height of the shunt plug in the sand mold is appropriate.

7.6 Box sealing

The sealing process is one of the key steps, and special attention should be paid to the operation. If the seal is not tight, molten steel will leak. After sealing is completed, the person in charge of welding shall check whether the sealing meets the requirements to ensure the welding quality.

7.6. 1 Cover the box with clean cardboard to prevent sand particles from falling into the sand mold to form slag inclusion;

7.6.2 The sealing should start from the bottom of the rail, proceed from bottom to top, and be plastered twice.

7.7 Control of preheating process

7.7. 1 Working pressure control

Oxygen pressure is 0.49MPa, propane pressure is 0.07MPa, and the preheating time of 60kg/m rail is about 5 minutes, and the color of rail head turns red.

In the process of pressure adjustment, the oxygen and propane switches on the preheating gun are all turned on, and the pressure regulator is adjusted clockwise to adjust the pressure of oxygen and propane.

7.7.2 Adjustment of preheating flame

Slightly open the propane valve first, then open the two valves alternately gradually by ignition until the propane valve is fully opened, and then adjust the flame size by adjusting the oxygen valve, so that the flame length is kept at 15-20mm, and the flame is neutral, and the preheating lance head should be 50mm away from the rail head;

7.7.3 Pay close attention to the whole preheating process.

In the preheating process, we should pay close attention to the discoloration process of the rail head, and the preheating time is about 5 minutes, and its color is bright red;

7.7.4 Preheating spray gun head should be adjusted to the center of rail gap to ensure preheating effect.

7.7.5 After preheating, turn off the oxygen switch first, with the gun head up, and pay attention to safety.

7.8 Use of Crucibles

7.8. 1 Check the crucible before use. Damaged and wet crucibles cannot be used.

7.8.2 sundries in the crucible shall be removed and the surface of fusible plug shall be cleaned.

7.8.3 Take out the flux from the flux bag, stir it evenly (pour it three times repeatedly), pour the flux into the crucible by rotation, and make its top form a cone, insert a high-temperature match, cover the crucible, put it into the shunt plug immediately after preheating, and put the crucible into the positioning groove at the top of the sand mold side template.

7.9 Flux High Temperature Reaction

Flux reaction time: 8- 15 seconds; Sedation time: 8- 18 seconds (if it exceeds 30s, the combustion will be uneven).

Note: In the process of flux reaction and pouring, the operator should stay away from the crucible for more than 3 meters to ensure personal safety. After the reaction, if the molten steel can't leak downward, let it cool in the crucible for 20 minutes before moving the crucible.

7. 10 form removal

1 After casting, remove the crucible and put it in a safe place, then remove the ash tray and pour the ash into the crucible to keep the environment clean. After pouring for 5 minutes, remove the side formwork and clamping device first, and then remove the bottom formwork.

Pay attention to a, be careful in the process of demolition, and don't take off the sand mold together, causing molten steel to flow out.

B, after dismantling, clean the rail surface in time to prevent the residue from pulling the rail surface when pushing the tumor.

7. 1 1 Promote tumor

The tumor began to advance 6.5 minutes after the casting was completed. After 20 minutes of tumor propulsion, the cast rod was taken out.

Note A. Due to insufficient hardness of welding head, premature pushing will deform the rail surface.

B, pushing the tumor too late will bring difficulties to pushing the tumor.

C when knocking off the cast bar, pay attention to the knocking direction, and do not knock from the inside out.

7. 12 thermal grinding

7. 12. 1 Rough grinding can be carried out after pushing the tumor. After welding, the temperature of the joint can only drop below 300 degrees before the car can pass.

7. 12.2 polish the welding head to make its profile the same as that of the rails on both sides.

7. 12.3 After grinding, the protrusion at the welding head shall be not less than 0.5mm. ..

7. 13 cooling and grinding

7. 13. 1 When the rail temperature drops to normal temperature, cold grinding shall be carried out. Polishing parts include rail top and inner working face, upper surface of rail bottom and rail bottom.

7. 13.2 make the rail surface level as a whole.

7. 13.3 There should be no obvious defects such as indentation, scratch and abrasion on both sides of the weld100 mm..

7. 13.4 The welding head shall be polished to 0-+0.3mm without dent. The grinding line with a speed of more than 200 kilometers per hour requires 0-+0.2 mm.

7. 14 appearance and flaw detection inspection

When the welding head cools to below 50℃, the rail welding head shall be inspected. Weld inspection is divided into visual inspection and instrument inspection. The defects on the weld surface mainly include scratches and bulges, which can be judged by visual inspection. The internal defects of weld mainly include porosity, inclusion and incomplete penetration. , can be detected by the instrument.

The surface roughness of the rail head working face after the weld shape is trimmed shall meet the following requirements: within 500mm on both sides of the weld center line, the surface roughness shall not be greater than 0.2mm, and the grinding depth of the base material on the rail top surface and the working edge on the rail head side shall not exceed 0.5mm..

7. After15 grinding, the rail head of the welded joint meets the following requirements.

7. 15. 1 There should be no crack;

7. 15.2 has 1 pores, and the maximum size is1mm;

7. 15.3 There are 1 pores, slag inclusion or sand inclusion in the area with a radius of 2mm at the joint between the lower jaw of the rail head and the edge of the welding rib, and the maximum size is1mm;

7. The weld bead surface of16 welded joint shall meet the following requirements:

7. 16. 1 can have at most three pores with the largest size not exceeding 2mm;

7. 16.2 The size of defects such as slag inclusion or sand inclusion on the surface of covered electrode shall conform to the provisions in the table below, and these defects shall not invade the cross section of the rail;

Maximum size of defects such as slag inclusion or sand inclusion on the surface of covered electrode.

Defect area mm2 Defect depth mm

≤ 10 ≤3

≤ 15 ≤2

≤20 ≤ 1

7. 17 Closing Work

7. 17. 1 Check the welded joint, make original records and write the welding serial number.

7. 17.2 clean the ballast bed and place the standard square pillow.

7. 17.3 Strengthen the tamping of two sleepers on both sides of the weld.

7. 17.4 restore the track to normal, and further clean up the welding site.

7. 17.5 clean up ash, waste and sand molds. , put into the crucible, and take it to the designated place for treatment when you leave. It is forbidden to throw along the railway, causing pollution along the railway.

Eight, welding joint straightness and surface quality requirements

8. 1 straightness requirements

The maximum allowable deviation of the straightness of rail head working face 1m length shall comply with the provisions of table 1.

Table 1 Maximum allowable deviation of flatness

Line design speed km/h Maximum deviation of rail top surface in vertical direction mm Maximum deviation of rail head side working edge in horizontal direction mm

160 +0.3 +0.3

Note: ① The "+"on the side of the rail head indicates depression, which enlarges the gauge;

② The "+"on the top surface of the rail indicates that it is higher than the datum plane of the rail bottom material.

8.2 surface quality requirements

8.2. 1 The surface roughness of the rail head working face after weld formation shall meet the following requirements: within the range of 100mm on both sides of the weld center line, the surface roughness shall not exceed 0.2 mm ... The grinding depth of the rail top base material and the rail head side working edge shall not exceed 0.2 mm..

8.2.2 There shall be no cracks, scratches, bumps, electrode burns, grinding burns and other damages on the surface of the welded joint and the rail nearby.

Nine, flaw detection

9. 1 Qualification requirements for inspectors

The flaw detector shall hold the second-class or above technical qualification certificate issued by the NDT Technical Qualification Committee of the Ministry of Railways, and be trained in rail weld flaw detection technology before working independently.

9.2 Inspection requirements for welded joints

9.2. 1 Ultrasonic inspection shall be carried out after rail welding, and inspection records shall be filled in. Records shall include instruments, probes, weld numbers, test data, flaw detection results and treatment opinions.

9.2.2 The temperature of welded joints during flaw detection shall not be higher than 40℃.

9.2.3 Before flaw detection, the detection system shall be calibrated.

9.2.4 Before scanning, check the surface roughness of the detected surface. There should be no rust and welding slag. The polished surface should be smooth and smooth, and the polishing range should meet the needs of flaw detection scanning.

9.2.5 Detect the rail head, rail waist and rail bottom respectively with double probes or single probes.

9.2.6 If internal and external defects are found, they shall be reported to the construction personnel in time and remedial measures shall be taken.

X. welding record

The welding operator shall record the welding process, and the content of the record shall be "Record Form of Rail Aluminized Welding Operation", and the record shall be kept for 3 years.

XI。 Safety and quality measures

1 1. 1 The personnel in each process shall receive safety technical training and can only take up their posts after passing the examination.

1 1.2 liquefied gas, oxygen cylinder, acetylene cylinder, etc. It should be arranged in the upwind direction and crosswind direction of welding and cutting flames, and not in the downwind direction of the flames. Standing and inversion are prohibited. Oxygen cylinders and gas cylinders should be 5m apart.

1 1.3 When the heater backfires and explodes, the oxygen should be turned off immediately, and then the gas should be turned off to extinguish the flame to prevent serious accidents.

1 1.4 During welding, it is forbidden to press or step on all gas pipes to ensure smooth air flow.

1 1.5 In the process of handling and operation, each working procedure should be operated in strict accordance with the operating procedures to prevent personal injury.

1 1.6 Necessary labor protection articles (work clothes, glasses, long leather gloves, etc. ) shall be provided during rail welding. Equipped with dry powder fire extinguisher.

1 1.7 There should be no volatile gas, inflammable and explosive articles near the construction site. If it exists, it is necessary to find a way to change or strive for safety protection measures before starting work.

1 1.8 The gas pipe should not be too close to the burnt-out heater to prevent explosion.

1 1.9 After heating, it is forbidden to touch all parts of the body to prevent burns.

1 1. 10 Before grinding, check whether the end milling cutter has leakage and works well. If there is any abnormality, immediately contact the maintenance electrician for maintenance. It is forbidden to connect privately to avoid personal accidents.

11.11It is forbidden to pollute the rail end face again. If there is pollution, it should be re-polished.

1 1. 12 Before ignition and welding, the required tools shall be put in order and properly positioned, and idle personnel are not allowed to enter the operation scope.

1 1. 13 The switch parts removed before welding shall be restored to their original positions;

1 1. 14 A desiccant and a wet and dry thermometer shall be prepared in the room where thermite welding materials are stored to ensure that the relative ambient temperature does not exceed 70%.

Twelve, aluminothermic welding operation procedures

12. 1 All construction machines, tools, materials and personnel are in place before construction preparation.

12.2 check the heating tools before starting each time to prevent air leakage.

12.3 before using the angle grinder, it is necessary to check whether the grinding wheel screws are tightened.

12.4 Adjust the alignment of rail gap and rail end. Don't stick the crowbar too deep. Two people should turn the number together and pull it out quickly to prevent the crowbar from hitting people.

12.5 sand mold installation must be carried out in strict accordance with the instructions.

12.6 workers must wear goggles before rail preheating to prevent eye injury. The on-site shift supervisor shall check whether the oxygen pipeline and gas pipeline are leaking. Oxygen bottles and liquefied bottles are strictly prohibited to be placed within 5m of the heater.

12.7 crucible installation must be carried out in accordance with the instructions.

12.8 before ignition and pouring, personnel must wear fire gloves, goggles and protective clothing to prevent burns.

12.8 before ripping, people around must stay away from the welding place to prevent people from being scalded by molten iron. Hot metal should be treated in a unified way and cannot be discarded casually. Before pushing the tumor, check whether the machine works properly.

12.9 When polishing, personnel must wear goggles, protective clothing, masks, helmets and heat insulating gloves.

Thirteen, aluminothermic welding safety operation procedures

13. 1 personnel engaged in turnout welding shall receive special training and master welding safety technology, and can only operate after passing the examination and obtaining the work permit.

13.2 personnel and materials before welding. Should be submitted for inspection, and the turnout welding can be carried out only after it is approved by the supervision department.

13.3 In the welding operation area, the surrounding flammable materials must be removed. If it cannot be removed, safe and reliable measures should be taken to protect it.

13.4 Before welding, carefully check whether the gas cylinder and oxygen cylinder are placed at a position 5 meters away; Do not wear oily gloves when installing the pressure gauge and opening the gas. Check whether the pipeline is firmly connected and whether there is any leakage.

13.5 strictly control the welding time to prevent the welding operation from stopping before the welding time and affecting the quality of welded rails.

13.6 Flux shall be stored in a dry room to prevent from being affected with damp, and shall be supervised and inspected by special personnel.

Attachment:

Rail welding machine and flux

Attached is the test report.

Thermite welding tool and flux

Serial number name model unit quantity remarks

1 2 kW gasoline generator 1

2 Angle grinder Table 3 is used for rust removal.

3 pieces 1m steel ruler 1m handle 1

4 LPG cylinders (pure propane) 6

5 oxygen pressure gauge 1

6 propane pressure gauge 1

7 oxygen flashback stopper 1

8 propane flashback plug 1

9 oxygen pipe m 10

10 propane pipeline

1 1 aluminothermic welding abrasive jacket 2

12 aluminothermic welding tumor pusher 4-stroke hydraulic tumor pusher 1

13 rail profiling grinding table 1

14 oxygen propane preheating gun, 1

15 rail temperature meter pay 2

16 stopwatch 2

17 ft 5m handle 2

18 feeler handle 2

19 copying grinder grinding wheel 20

20 Angle grinder grinding wheel blade 50

2 1 rail saw grinding wheel diameter 420mm 50

22 Wire Brush Handle 20

23 sledgehammer 1

24-handle small hammer 1

25 triangle iron is long 18cm, short 5cm and thick 2cm.

26 measuring points with wedge plug gauge 1.

27 Sleeve of Rail Puller 1

28 crowbar handle 2

29 adjustable wrench maximum opening width 20mmm put 2.

The maximum opening width is 30mm. Put 2

The maximum opening width is 45 mm, and 2.

30 sets 144 welding equipment and flux in Letak, France, depending on the rail head, including flux, sand mold, sealing mud, crucible, sealing paste, etc.

3 1 mask helmet 10

32 pairs of insulating gloves 10

Protective clothing 10

34 goggles 10

35 trolley cars 1

36 Welding head insulation cover 1