The crane runs on crane rail, rail rail and square steel.The top of the rail is convex, and the bottom is a slab with a certain width, increasing the contact surface of the base.The cross section of the track is the zigzag pattern, with good bending strength.Square steel can be regarded as a flat top rail, and because of the large wear and tear of the wheel, it is generally used only for the smaller, slower, and less frequently working cranes.The steel rails are generally rolled in carbon and manganese steel (C = 0.5% ~ 0.8%, Mn = 0.6% ~ 1.5%).The typical material of crane track is U71Mn steel.Square steel is made mainly of Q275 square or flat steel.Crane rail is used as the special section steel rail for crane cart and car, the standard length is 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5 and 8 kinds.The common specifications are QU7O, QU8O, QU100, QU120, and the number in the end indicates the width of the orbital head.The railway rail is divided into rail and light rail, and the steel rail is used for each meter.Steel rail, weighing more than 30 kg/m, is a heavy rail.The standard rail length is 12.50 m and 25.00 m 2 specifications.Light rail is not more than 30 kg/m rail, usually 5 ~ 12 m.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. The installation of crane rails
There are two types of rail beams used for the installation of orbit: one is steel structure girder, and one is concrete prefabricated beams.The concrete prefabricated beam must be kept for the installation time to wear bolts, or to bury bolts in the concrete precast beams.The installation method of crane rails is used for fixed pressing, hook screw, welding and bolts.In order to make the adjustment of the horizontal direction, the holes in the rail plate are usually made up, and the vertical adjustment can be added under the rail.The orbiter is designed with a design
It is rigid enough to make a single hole or double hole according to the size of the force.The gear can be soldered on the track only when the rails are connected to the rails or the fixed steel pads on the rail beams.
3.The installation of the rail beam before the track is laid
3.1 Requirements of rail bearer of coagulation
(1) Track beam production must ensure that the reserved along the beam transverse and longitudinal bolt hole position deviation in 5 mm or less, bolt hole diameter is bigger than the bolt diameter 2 ~ 7 mm, flat beam top surface requirement, but shall not wipe smooth.
(2) The installation deviation of the track beam
You must meet the following requirements, otherwise you will be able to adjust the rail beams before you allow the concrete to change.
The center position of the center of the beam is less than or equal to 5 mm
The height of the top of the beam is about +10 mm ~ 5mm
The displacement deviation of the bolt hole and the reserved bolt on the beam center is less than or equal to 5mm.
(3) The construction requirements of the concrete level shall be made
The level of concrete leveling is C30, and the thickness is 30 ~ 50 mm.
The installation deviation of the rail beam should be checked before the concrete leveling, if not, the rail beam should be adjusted.
According to the track on the surface of the beam the measured elevation, determine a suitable concrete leveling layer top surface control level, on the track beam every 2.4 ~ 3.0 m to set up a control elevation datum.
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.
The top surface of the flat layer must be flat and flat, and no stone or other surface should be allowed to be used for leveling the surface of cement mortar
Check at any time measured with instrument in the construction, at the top of the screed-coat must meet the following requirements: bolt at the top of the range of 400 mm width not levelness 5 mm or less arbitrary length of 6.0 m interior bolt top surface elevation difference m + 3 m;The top of all the bolts is high and minus 5m m.
The concrete adopts mechanical mixing, and the construction should be strengthened, and when the concrete test block reaches 75% strength design value, the orbit installation can be carried out.
3.2 The requirements of the steel structure rail girder
(1) The span of the beam of the track is less than or equal to h / 500, and h is the beam of the track beam.
(2) The horizontal side of the track beam is less than 1/1500, and the net 10 mm, l is the beam length of the track beam.
(3) The vertical direction of the beam is less than 10 mm.
(4) The deviation of the center of the orbit beam is less than or equal to 5mm for the design of the positioning axis, and if it is not suitable, it should be adjusted to the position of the beam.
(5) The height difference between the top of the beam on the same cross section of the cross section is less than 10 mm, and the other is less than 15 mm.
(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 upper surface of the two rail beams is less than or equal to 1 mm, and the center side is less than or equal to 3 mm.
4. Crane rail joint
4.1 Pre-weld preparation
Before the welding of the crane rail joint, it is necessary to clear the groove and the oil, rust and so on until the metal luster is exposed.The welding material is based on the strong principle, match the basic electrode, its number J857 (national standard e8515-g), the skin type is low hydrogen type.Electrode J857 subject to review of qualified, before any welding is 350 ℃ ~ 400 ℃ drying 1 h.
4.2 Orbital welding deformation control of 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 reduce the padding of the rail head to 20 mm 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 orbit 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.At any time in the whole process of welding, must monitor the deformation of the rail joint with straight steel ruler, adjust the height of joint and tight pine board 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, the two steel rails must be aligned, and no skew or error should be made.
Prior to welding and welding process, should be strict inspection and ensure the position of the center line of two rail in a line, in order to prevent the orbital welding is completed, usually have bent not straight phenomenon occurred.When welding the rail joints of the rails with curved hook bolts, the above method can be used according to the specific situation, and the temporary fixture shall be set up for welding.
The sequence of welded rail joints is made up of the bottom of the track, and then the rails and the rails of the rails are stacked up and down the road, and then the surrounding area is repaired.Two rail end in the range of 4 mm, o preheated at the same time, 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;The subsequent layers can be used (130 + + 15) A, and each layer shall be cleanly cleaned to continue the welding.Rails welding: the current is 130 ~ 140 A, welding from the lower part of the waist, and paying attention to the slag.Rail head welding: the current 130 ~ 140 A, when the copper plate is installed, begin to weld and notice the slag once;In the end, the welding process is carried out for the unsoldered full area around the weld.
4.4 Notice in the process of track welding
In each layer of welding welding when the wave, especially in the welds rail bottom of each layer of welding wave, you should use one electrode welding, avoid or move between electrode and arc breaking, 2 layer before and after welding the welds should be the opposite direction of the wave;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, it is necessary to prevent the rain from getting wet before it is cooled.The hot copper plate can be removed with water cooling, so that it can be used again.
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;Eliminating stress heat treatment adopt welding nozzle around the rail head, rail waist rail and bottom repeated heating, should as far as possible to track the whole cross section of uniform heating, paying special attention to the bottom of the rail heating quality.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 at least 20 ~ 30 mm, and it will be kept warm and cold until the temperature is cold.
4.6 The grinding of the 4.6 rail joint
The steel rail welded joint has eliminated the stress heat treatment and cooled to the atmospheric temperature, and the welding seam for the top surface of the orbit and the two sides is smoothed.When the welding is raised too big, grinding the machine with grinding wheel, until it is flush with the rail head, it will finish polishing the surface.
5. The joint of the plant expansion joint is handled
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 a splice splint that is processed by rail head, and the clearance is 50mm.
6. Crane track installation
When the crane cart brakes, it produces a vertical thrust.If the car brakes, it creates a lateral thrust.If the big, small car brake simultaneously, it produces a synthetic motive force, which makes the orbit bear an oblique thrust.Such as rail installation into one is generally higher than the other, the overall crane will move to the low side, thus increasing the orbit on the transverse force, caused by the crane operation "chew", resulting from the collision accident easily.
The current orbit connection is about: pressing plate fixed method, hook bolt fixed method and so on.
Clamp fixed method
The pressure plate is fastened by the nut 3 screw to tighten the rail on the crane rail beam.When the crane is caused by some kind of mechanical or electrical reasons, running all the way ", will inevitably cause the cart wheel rim produces a lateral thrust to orbit, the force by rail to clamp (clamp installation need to adjust the distance, so will be growing system of bolt hole hole), even if the pressure plate installation, plus the pine or square pad spot welding, large tonnage crane rail also difficult to guarantee.Because of the vertical pressure and no lateral force, the lateral displacement of the rail is inevitable.
Hook bolt fixation
This type of connection is fixed by the nut 6, which is attached to the rail beam, and the hook bolts are threaded through the rails.The hook bolt has a large lateral force and the vertical force is small.When the crane wheel pressing repeatedly, rail pad easily derailed string, the elevation changes in orbit, causes a crane running "climbing" or "top", and cannot run normally.In addition, this kind of join method, the orbit is to drill hole, increase the mechanical processing quantity, increase the project cost.
There are some drawbacks to the two forms of join.The pressure plate fixation method has the greater vertical pressure, but the horizontal force is easy to make the track produce lateral displacement.The hook bolt fixed method has a large lateral force, but no vertical pressure, and increases the mechanical processing quantity.
Used in trajectory, repairing experience for many years has proved that: to apply the above two methods of connection joint, namely, two pairs of clamp connection method, interval of a pair of hook bolt fixed method is effective.In this way, the advantage of the vertical pressure of the pressure plate is put into play.Make full use of the advantage of the horizontal force of the hook bolt to ensure that the track does not produce the side bend, and the cart is not easy to "chew the way".This structure means that the installation accuracy of the track is not easily changed, and the reliability of the link is guaranteed.Therefore, it also does not need to adjust the high elevation of the track and the bending press nut, and improve the efficiency of the crane and ensure its safe and reliable operation.