In engineering, crane rail installation is an engineering field between mechanical and civil engineering.Orbital installations are usually installed by plant construction workers, while cranes are installed by units with crane installation qualifications. They are often disjointed.In engineering construction, the installation of rail rail beams and crane rails is usually completed by two majors (such as civil and mechanical installation), and there is a disconnect between the two majors.Therefore, it is difficult to guarantee the installation quality of crane rails.The installation of crane rails directly affects the quality of crane operation.The quality of the crane rails can be guaranteed only if the quality control is grasped at the source.
1. Crane Rails
Crane rails, railway rail and square steel.The top of the rail is convex, and the bottom is a plate with a certain width, which increases the contact surface with the foundation.The cross section of the track is mostly zigzag, with good bending strength.Square steel can be regarded as the flat top rail, because of the large wear of the wheel, generally used only for the small weight, slow speed, the work less frequent crane.Steel rail usually consists of carbon and manganese steel (C = 015% ~ 018%, Mn = 016% ~ 115%).The typical material of crane track is U71Mn steel.Square steel is mainly made of Q275 steel or flat side. Crane rail is used as a crane cart and the car in the special section of rail, the standard length of 9, 915, 10, 1015, 11, 1115, 12, 1215, etc. 8.Common specifications are QU70, QU80, QU100, QU120, and the number behind QU indicates the width of the track head.Railway rail track and rail are divided into two kinds of rail and light rail.Rail, which weighs more than 30kg/m, belongs to heavy rail.The standard rail length is 12150m and 25100m2.The light rail is not more than 30kg/m rail, usually 5 ~ 12m.Light rail steel, most of them are killed steel of ordinary carbon structural steel and half killed steel, in order to improve the wear resistance and corrosion resistance of steel, in recent years, use the alloy elements such as Mn, Si, P of the low alloy steel.
2. Installation of Crane Rails
There are two kinds of rail beams used for installation of rails: one is steel structure beam and one is concrete prefabricated beam.The concrete precast beam must have embedded holes for the installation of bolts, or embedded bolts in the concrete precast beam.The installation method of crane rails is used for fixed pressing plate, hook screw fixation, welding and bolting.In order to adjust the horizontal direction, the holes in the rail clamp are usually made of growth holes, and the adjustment of the vertical direction can be added under the rail.When designing, the rail pressure plate shall be rigid enough to form a single hole or double hole according to the size of the force.The gears can be soldered on the track only when the rails are connected to the rail beam or the fixed steel gasket on the rail beam.
3. Installation Requirements for Rail Beams Before the Track is Laid
3.1 Requirements for Concrete Rail Beams
(1) When the beam is made, the position deviation of the reserved bolt hole in the transverse and longitudinal direction of the beam must be guaranteed to be equal to 5mm. The diameter of the bolt hole is 2 ~ 7mm larger than the diameter of the bolt, and the top surface of the beam shall be flat, but not smooth.
(2) The installation deviation of the rail beam must meet the following requirements, otherwise the concrete may be adjusted after the rail beam is adjusted.The deviation of the center of the beam center is less than 5mm.The height of the top of the beam is the deviation of the design elevation of 10mm-5mm.
The displacement deviation of the bolt hole and reserved bolt on the beam center is less than 5mm.
(3) Construction requirements of concrete leveling layer
① The strength grade of the concrete leveling layer is C30 and the thickness is 30 ~ 50mm.
② The installation deviation of the rail beam should be inspected before the concrete leveling floor, and the rail beam should be adjusted if it does not meet the requirements.
③ According to the measured elevation of the track beam, the elevation of the top surface of a suitable concrete leveling layer is determined, and a reference point of control elevation is set at every 214 ~ 310m on the track beam.
④ Instrument was used to measure and adjust the benchmark level, set at the top of the screed-coat elevation datum line, and then install the template, clear track beam top surface and sundry, bolt hole and the bolt hole plug, top of the concrete after sprinkling water wet.
⑤ The top surface of the leveling layer must be flat and flat, no stone exposed or uneven, and the surface of cement mortar shall not be used for leveling.
⑥ In the construction, the equipment should be used to measure the inspection at any time. The top surface of the leveling layer must meet the following requirements: the top surface of the bolt shall be no more than 5mm in the width of 400mm;The top elevation difference of the top surface of any 610m length interior bolts is 3mm;The top elevation difference of the whole length of the bolt is plus or minus 5m.
⑦ The concrete adopts mechanical stirring, and should be strengthened during construction. When the concrete test block reaches 75% of the design value, the rail installation can be carried out.
3.2 Requirements for Steel Structure Rail Beams
(1) The span of the beam of the track beam is less than or equal to h / 500 and h is the beam height of the track beam.
(2) The horizontal side of the track beam is less than or equal to l / 1500, and the net 10mm, l is the beam length of the rail beam.
(3) The vertical direction of the rail beam is less than 10mm.
(4) The deviation of the center of the rail beam center is less than or equal to 5mm for the design of the positioning axis. If it does not meet the requirements, it is necessary to adjust the positioning of the rail beam to install the track.
(5) The height difference of the top surface of the cross-sectional rail beam is less than 10mm at the base and no more than 15m at other points.
(6) With column track beam top surface height difference between adjacent 2 column l / 1500 or less, and ≯ 10 mm, l long for track beam beam.
(7) The height difference between the top surface of the 2 rail beam is less than 1mm and the center side is not equal to 3mm.
4 Crane Rail Joint
4.1 Preparation Before Welding
Before the welding of the crane rail joint, carefully clear the groove and the oil, rust and other contaminants until the metallic luster is revealed.Welding material basis and other strong principles, matching basic electrode, its number J857 (national standard)
4.2 Control of Rail Welding Deformation
The height of the rail end up in advance, according to the rail of the varieties, length and fixed, and environmental factors such as temperature, use in advance, with copper plate and carbon steel rail end up 30 ~ 40 mm, use has been produced good bolt and clamp connection, tighten the nut that rail is fixed on the rail beam, each fixed point near the rail joint set at least four places.After soldering the bottom of the rail, loosen the clamp and lower the rail end to 20mm and tighten the clamp.When welding is in line with the waist, gradually reduce the plate height, when welding the rail waist parts, should be removed all plate, and loosen the clamp, the rail should be joint on a small become warped values, in the process of welded rail head, according to the rail recovery of flat, decide whether or not to tighten the clamp nut.In the process of all welding, it is necessary to check the deformation of the rail joint at any time with straight steel ruler, adjust the height of the joint and tighten the pressure plate at any time to control the deformation of the rail joint.Fixed in front of the welds rail joint, the gap between two rail end are on wide below narrow, will be subject to the bottom of the rail gap, shall not be less than 12 mm, also shoulds not be too wide, general control in the range of 15 to 18 mm.In the adjustment of the fixed rail joint, in addition to the size of the end clearance, two rail terminals must be aligned, and no skew and stagger will be allowed.In the process of welding before and during welding, it is necessary to strictly check and ensure that the position of 2 rails center line is on a line to prevent the track welding from being completed.When welding the rail joint with the curved hook bolt, it can be used according to the specific situation to refer to the above method to set up the temporary fixture fixed rail for welding.
The sequence of welded rail joint is made up of bottom, first track bottom, rail head, track by layer by road, and then repair the surrounding.Two rail end in the range of 40 mm, simultaneously preheating, preheat and interpass temperature control at 300 ℃ ~ 350 ℃.(base) : the first layer welding current is 120 a ~ 130 a, in order to prevent permanent steel plate burning through and will melt copper plate, and thus to minimize weed out the difficulty of the copper plate and shorten the track air cooling time, help keep the interpass temperature, prevent hardening;In the future, the layers can be used (130 + 15) A, and each layer of welding must be cleaned to remove the welding.Track welding: current 130 ~ 140A, welding from the lower part of the waist, pay attention to the slag.
Rail head welding: current 130 ~ 140A, after the copper plate is installed, start welding, pay attention to every layer of slag;In the end, the welding process of unsoldered joints around the weld is carried out.
4.4 Precautions in the Process of Rail Welding
In the welding wave at each layer of the welding, especially in the welding wave at the bottom of the welded rail, the welding rod of l root shall be used for welding, and the welding electrode shall be avoided in the middle, and the welding direction of the two layers shall be the opposite.Each rail joint welding work shall be carried out continuously, in order to keep the end of the rail welding at high temperatures (300 ℃ ~ 350 ℃).After welding, when the stress heat treatment has not been cooled before cooling, it is necessary to prevent rain and other wet;Hot copper plates can be removed and dipped in water so that they can be reused next time.
4.5 Stress Heat Treatment (Flame Heating)
Elimination of rail end after completion of the welding stress is one of the important measures to improve the quality of welding, heat treatment for at relatively low temperatures such as winter construction, etc.), welding of rail, must adopt the measure;In the treatment of stress heat treatment, the gas welding nozzle is used to heat the rail head, the rail and the bottom of the rail repeatedly, so as to make the whole section of the track to be heated evenly and pay special attention to the heating quality of the rail.Eliminating stress of heat treatment temperature of 620 ℃ ~ 650 ℃, from the weld center is 40 mm as eliminating stress of heat treatment on both sides of the scope;After the temperature of the stress heat treatment is reached, the heating must be kept at more than 20 ~ 30min, and the heat insulation of the needling carpet is good.
4.6 The Grinding of the Rail Joint
After the steel rail welded joint has been removed the stress heat treatment and cooled to the atmospheric temperature, the welding seam of the top surface and the two sides of the rail will be smoothed.When the welding bulge is too large, grinding the polishing machine with grinding wheel, until it is flush with the rail head, finish the surface finish.
5. Treatment of Rail Joints in the Expansion Joints of the Workshop
Rail joint processing plant expansion joints usually has two kinds: one kind of use splint or fish plate connection, rail USES 45 ° inclined joint, clearance to 10 mm.The other type adopts the splicing splint which is processed by rail head, and the clearance is 50mm.