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Anonymous users2024-02-06The main content of concrete crane girder correction includes verticality and plane position correction, both of which should be carried out at the same time. The elevation of the concrete crane girder, because the column has been controlled by the elevation of the bottom surface of the powder foundation when the column is hoisted, and a thicker cushion is still needed between the crane girder and the crane track, so it generally does not need to be corrected.
1 Perpendicularity correction.
The verticality of the crane girder is checked with a ruler and a line hammer. The T-shaped crane girder measures the verticality of both ends, and the fish-belly crane girder measures the verticality of both sides of the middle span.
The permissible deviation of the verticality of the crane girder is that if the twist deviation of the crane girder itself is large, the deflection of both ends of the crane girder is reversed by correction, and the deflection value should be within 5mm; If the fish belly crane girder itself is distorted, it can be corrected to make the difference between the deviation values of the opposite direction on both sides within 5mm.
When correcting the verticality of the crane beam, the inclined cushion block needs to be cushioned between the bottom end of the crane beam and the corbel surface of the column, for this purpose, the crane beam should be lifted, the jack and the like can be used according to the weight of the crane beam, and the inverted chain can also be hung on the column or the roof truss, and one end of the horn of the crane beam needs to be lifted up.
2 Plane position correction.
Crane beam plane position correction, including straightness (so that the center line of each beam on the same longitudinal axis is in a straight line) and span. Generally, the crane beam with a length of 6m and less than 5t can be corrected by the wire drawing method and the instrument pay-off method. Crane girders with a length of 12m and more than 5t are often corrected by the method of calibration while hanging.
1) Wire drawing method: according to the column axis, use theodolite to put the center line of the crane beam on the crane beam of one span and four corners, and check the span with a steel ruler, and then pull a 16 18 steel wire on the two center lines respectively. The middle part of the steel wire is supported by round steel, the two ends are about 20cm high, and the hanging weight is tightened, after the steel wire is drawn, all the crane beams that do not coincide with the steel wire should be corrected with a crowbar.
2) Instrument pay-off method: use theodolite to put a correction reference line equal to the distance from the center line of the crane beam on the side of each column. The distance a value from the correction baseline to the center line of the crane girder shall be determined by the pay-off.
When calibrating, where the distance from the center line of the crane beam to the reference line of its column side is not equal to the value of A, it is corrected with a crowbar.
3) Hanging while calibration method: before the crane girder is hoisted, the theodolite is erected on the ground at one end of the plant span about 40 60cm from the center line of the crane girder, so that the line of sight of the theodolite is parallel to the center line of the crane girder, and then draw two ** on a wooden ruler, marked A and B, the distance of these two ** must be equal to the distance from the theodolite line of sight to the center line of the crane girder. When hoisting, a line A of the wooden ruler coincides with the center line of the crane beam, and the other line B of the wooden ruler is seen with a theodolite, and the crane beam is tossed with a pry bar, so that **B coincides with the cross vertical line on the theodolite telescope.
When using this method, it is necessary to frequently visually check the straightness of the installed crane girder, and use a steel ruler to check the span to prevent errors due to the movement of the theodolite during operation.
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Anonymous users2024-02-05What requirements should be met for the production of crane girders?
When the crane girder is made, the factory splicing of the flange plate and the web should use the butt weld with the arc striking plate, and the arc striking plate should be cut off and polished after the docking is completed. The crane girder production should meet the requirements:
1) The butt weld of the upper and lower flange imitation code plate generally requires the use of automatic welding of straight seam butt, and requires weld penetration. When the summer flange butt weld is in the range of 1 3 in the span, it is advisable to use 45o 55o oblique seam butt;
2) The factory splicing joint of the flange or web should not be located on the same cross-section, and should be staggered by 200mm as far as possible, and the joint position should be located within the range of about 1 3 1 4 beam span from the support;
For the butt weld in the direction of the web longitudinal and horizontal beam, a T-shaped cross can also be used as a cross-shaped cross, and the distance between the intersection points shall not be less than 200mm for the T-shaped crossing; When the splicing weld intersects with the stiffener, the fillet weld connecting the stiffener and the web should be interrupted, and the distance between its end and the splicing weld is about 50mm.
3) The arc striking plate selected for butt weld must be the same as the material and thickness of the base metal, and the cut form must also be the same as that of the base metal.
The connection between the crane beam and the braking structure, the heavy-duty working crane beam should be connected by high-strength bolts, and the light and intermediate working crane beam can be welded on site. The tensile flange of the crane girder shall not be welded with the suspension equipment parts, and the connection between the tensile flange of the crane girder and the horizontal support shall be connected by bolts and shall not be welded.
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Anonymous users2024-02-04The crane operation is more dangerous, and the crane beam.
The installation should be standardized to ensure the safety of the crane operation. The crane installation needs to pay attention to the following points:
Before the installation of the steel crane girder, the actual elevation of the corbel after the column installation should be measured, so that the construction error of the elevation can be adjusted when the crane girder is installed, so as to prevent the accumulation of errors.
The installation sequence of the crane girder is as follows: install the crane girder and install the auxiliary truss.
Install the brake beam.
Crane girder lifting should be tied with a sling or with a reliable clamp. The binding point is determined according to the weight and length of the crane beam, generally at the two ends of the symmetrical center of gravity of the crane beam, and the sling angle should be greater than 45 degrees.
After the crane girder is placed, the flange plate on the crane girder should be connected and fixed with a connecting plate with a connecting plate to prevent the crane girder from moving longitudinally and toppling laterally after the crane loosens the hook.
The crane girder correction should be carried out after all the bolts are installed, and the crane girder is displaced and changed when the bolts are installed with Sundong high defense; It is strictly forbidden to weld suspension objects and fixtures on the lower flange and web of the crane girder.
The calibration of the crane beam should be adjusted first, and the center line and span should be corrected after titanium.
Measure the elevation of the crane girder, set the instrument on the crane girder surface, and each crane girder should observe three points (both ends and the midpoint).
If there is a negative deviation in the elevation of the crane girder installation, an iron backing plate can be placed between the column corbel surface and the lower flange plate of the crane girder. However, the backing plate shall not exceed three layers, and shall be placed on the end web or stiffener of the crane girder.
Below, and the area of the backing plate shall not be less than 60% of the area of the contact part between the crane beam and the corbel.
Crane girder centerline adjustment method:
Every 5 6 column spacing welds a crossbar on the column side, the length exceeds the center line of the crane beam, and the height is about 50mm higher than the crane beam surface;
Use the instrument to guide the crane girder control center line to each crossbar;
After connecting the points with a thin wire, the installation deviation of the crane girder is checked by the hanging wire hammer method and its deviation value is adjusted.
The span of the crane girder should be measured and checked with a long steel ruler.
The correction of the crane girder and track should be carried out after the main members are fixed. The ruler is fixed immediately after the calibration, and the fixing sequence is to install the bolt first and then weld.
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