The method of repair of structural elements

 

(57) Abstract:

Usage: repair and restoration of metal, made of metal and casting thickness of not more than 40 mm, including the construction of bridges, elements and nodes handling and road-building machines. The inventive method is that at the end of the crack drill hole, after which produce cutting cracks and welding, with a hole drilled at a distance from the end of the crack is equal to 0.4 - 0.5 in diameter, in the direction of the tangent to the radius of curvature of the plot arc near the end of the crack and cutting crack is produced at an angle 50o75o. After welding the crack opening rassverlivajut to diameter, depending on the thickness of the structural element. After welding cracks also produce multiple, but not less than three, the loading design with excess voltage in the element by 25% from nominal and single loading design to the nominal level of stresses in the element. Cutting cracks are produced with variable angle cutting along its length. 2 C.p. f-crystals, 3 ill.

The invention relates to the field of repair of constructions made of metal and pouring and road-building machines.

There is a method of repair of structural elements with a thickness of 5 to 25 mm in the case of cracks, namely, that limit the spread of cracks by drilling holes near the end of the crack, after which the edges of the crack is cut for welding and crack brewed along the entire length, and made a hole is not brewed. The end and the beginning of the welding seam smooth out any mechanical method [1]

The disadvantage of this method is that it does not specify rules for the selection of the diameter of the running of the hole depending on the thickness of the element and does not take into account the level and distribution of residual welding stresses, the value of which under certain conditions can reach in certain areas of the weld yield stress, which can lead to a significant reduction of the fatigue strength of a structural element.

There are also known methods of repair of structural elements, namely, that limit the propagation of cracks by drilling their end with the installation of a completed bolt hole [2] or a group of bolts near the end of the cracks [3] are then tightened to create the field (s), compressive stresses. The disadvantages of these methods mo is free access to the defective portions of the elements on both sides, and for a full recovery of the carrying capacity of the elements of steel structures, installation of reinforcing plates (plates) on the defective place is impossible.

The aim of the present invention is to improve the quality of the repair and restoration of the bearing capacity of structural members and increase their service life.

To achieve this goal hole drilled at a distance from the end of the crack is equal to 0.4 to 0.5 of its diameter, in the direction of the tangent to the radius of curvature of the plot arc near the end of the crack and cutting crack is produced at an angle 50o75oand after welding the crack opening rassverlivajut to diameter, depending on the thickness of the structural element. After welding cracks produce multiple, but not less than three, the loading design with excess voltage in the element by 25% from nominal and single loading design to the nominal level of stresses in the element. Cutting cracks are produced with variable angle cutting along its length.

In Fig. 1 shows a section of the element structures with crack;

in Fig. 2 cutting the cracks in the section AA of Fig. 1;

in Fig. 3, in the section B-B.

Method of repair of items con is the construction with crack 2 in the direction of its propagation along the tangent 3 to the radius of curvature R of the plot arc near the end of the crack 2 drill 4 hole diameter d110 12 mm centre distance (0,4 0,5)d1from the identified visual way of end cracks 2 (Fig. 1). Edge sewerlines cracks cut for welding any mechanically (Fig. 2, 3) up to a previously completed holes d1and to ensure a more favourable distribution of welding residual stresses after welding cracks 2 the angle a of the cutting edges may be variable for each structural element 1 of a thickness not exceeding 16 mm: from a 50o5othe free edges 5 of the element 1 (Fig. 1) to a 75o5o(Fig. 3) near the end of the crack 2 (Fig. 1) with smooth measurement along its length or a 50o5othe length (0,3 0,4)lTr.from the free edge 5 of the element 1 and a 75o5othe length (0,7-0,6)lTr.or constant for items 1 thickness 16 of 40 mm and equal to a 50o5owhere lTr.the maximum length of the identified visual or otherwise cracks.

Welding cracks produced by any method available to provide the necessary strength and plastic characteristics of the compounds. To reduce the residual stresses after welding and removal of possible defects in the area of the end of the welding seam should:

1. to produce agreeeee 25%

2. after three loading of the metal element in the fourth process of loading up to the level of nominal voltage, nezavisne 4 hole diameter 10 to 12 mm drilled to the proper diameter d2determined by the thickness of the element 1 with crack 2 (Fig. 1):

d216 mm when d < 8 mm;

d20,0332+ 14 mm at 16d8;

d2=24, 40d>16 mm with subsequent review of the conditions of strength;

3. reamed hole 4 is not brewed, but its edge is treated mechanically to remove burrs and the like defects with the aim of improving the fatigue strength of the metal elements.

After performing strength calculation, if necessary, to produce amplification of the structural element, for example by installing plates, overlapping the crack. If there is a crack has a maximum length lTr.not exceeding (5 10)d, where d is the thickness of the structural element, after brewing cracks subsequent drilling of 4 holes with a diameter of d1up to a diameter d2can be carried out without prior loading of the structural element 1.

The above method of repair of structural elements effective in R is vechnosti not less than 30% in comparison with the known, currently used, methods of repair of structures with cracks.

1. The method of repair of structural elements made of metal, namely, that at the end of the crack drill hole, after which produce cutting cracks and welding, characterized in that the drill hole at a distance from the end of the crack is equal to 0.4 0.05 to its diameter in the direction of the tangent to the radius of curvature of the plot arc near the end of the crack and cutting crack is produced at an angle 5075and after welding cracks holes rassverlivajut to diameter, depending on the thickness of the structural element.

2. The method according to p. 1, wherein after welding cracks produce multiple, but not less than three, loading design with excess voltage in the element by 25% from nominal and single loading to the nominal level of stresses in the element.

3. The method according to p. 1, characterized in that the cutting cracks are produced with variable angle cutting along its length.

 

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EFFECT: increased longevity of gas pipelines.

4 dwg, 1 ex

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