RU2314184C1 - Welded beam production method - Google Patents

Abstract

FIELD: construction, particularly welded structures adapted for bridge, industrial and civil construction.

SUBSTANCE: method involves connecting beam 4 belt 7 and wall 6 by clips; performing prior heating welded seam zone before beam welding from outer belt 7 side in front of wall 6 with the use of heating device 8 so that primary bent with negative angular deformation is created; welding the beam with the use of welding device 5 arranged in series with heating device 5 and spaced S distance therefrom, wherein S distance is characterized by time interval Δτ=τ₂-τ₁, that is time when temperature of inner and outer beam belt side becomes equal to temperature of beam wall in place of beam wall joining to belt and is maintained within range defined by maximal and minimal admissible values in dependence of beam cross-section, welded seam thickness and heating device power. Here τ₁ is time interval between prior beam heating and time point when temperature of inner and outer beam belt side and temperature of beam wall in place of beam wall connection to belt reduces to maximal admissible value. τ₂ is time interval between prior beam heating and time point when temperature of inner and outer beam belt side and temperature of beam wall in place of beam wall connection to belt reduces to minimal admissible value. After welded seam forming from one beam wall side beam is immediately turned and welded from another beam wall side for total belt welding.

EFFECT: increased efficiency.

2 cl, 5 dwg

Description

The invention relates to the manufacturing technology of welded metal structures and can be used in bridge construction, industrial and civil engineering.

A known method of manufacturing a welded beam, which consists in assembling the beam, attaching the belt of the beam to the wall using tacks (short welds), moving the beam to the welding stand, welding the beam, moving the beam to the devices for editing the mushroom shape and editing the mushroom shape (E.L. Voronov , L.F. Kolesnichenko. "Equipment of metal structures factories." M., Mechanical Engineering, 1981, p. 159).

The disadvantage of this method is that the welded high-strength joints of bridge steels are defective.

The closest in technical essence and the achieved result to the claimed one is a method of manufacturing a welded beam, comprising the steps of assembling the beam on tacks, preheating the weld zone before welding and eliminating residual deformations of the mushroom shape (E.L. Voronov, L.F. Kolesnichenko. “Equipment factories of metal structures. ”M., Mechanical Engineering, 1981, p. 159).

The disadvantage of this method is its high complexity.

The objective of the invention was to reduce the complexity and energy consumption of the manufacturing process of welded metal structures.

To achieve the specified technical result in a method of manufacturing a welded beam, including assembling the belt and the wall of the beam at the tacks, preheating the zone of the weld before welding and welding, preheating the zone of the weld before welding is carried out from the outside of the belt opposite the wall of the beam with a heating device with the formation of a preliminary bending with negative angular deformations, and welding is carried out by a welding device, which is arranged in series with the heating the distance from it, in which, after a time interval Δτ = τ ₂ -τ _{1, the} temperature on the outer and inner sides of the beam belt and the temperature in the beam wall at the point of its adjoining to the belt equalize and are in the interval between the maximum and minimum acceptable values depending on the transverse section of the beam, thickness of the weld and power of the heating device, where τ ₁ is the time after the preheating of the weld zone, through which the temperature on the outer and inner sides of the beam zone and the temperature in the walls the beam beam at the point where it adjoins the belt decreases to the maximum allowable, τ ₂ is the time after the preheating of the weld zone, through which the temperature on the outer and inner side of the beam belt and the temperature in the beam wall at the point of contact with the belt decreases to the minimum allowable in this case, after the seam is applied on one side of the wall, the beam is immediately turned over and the seam is welded on the other side of the wall, completely welding the belt.

In addition, the welding device can be located at a distance from the heating device, in which the time τ ₁ is 3 minutes, and the time interval Δτ is 20 minutes.

The invention is illustrated by drawings, where

figure 1 shows a General view of the stand for welding, in a perspective view;

figure 2 presents a diagram of a device for heating the beam from the outside of its belt;

figure 3 presents the location of the characteristic points of the cross section of the welded beams, which determine the process;

figure 4 presents graphs of changes over time of temperature at characteristic points of the cross section of the beam (see figure 3);

figure 5 presents graphs of dependencies of the ratio of the efficiency of deformation of a single sheet and brand.

The essence of the method is as follows.

A beam is assembled at the assembly stand. Belts are attached to the wall using short welds - “tacks”. Next, the assembled beam using a device for lifting, transporting and recanting the welded beams is installed on a stand for welding beams. Preheat the weld zone before welding from the outside of the belt opposite the beam wall with a heating device to form a preliminary bend with negative angular deformations. Welding is performed by a welding device, which is arranged in series with the heating device at such a distance from it that, after a time interval Δτ = τ ₂ -τ _{1, the} temperature on the outer and inner sides of the beam belt and the temperature in the wall of the beam at its junction with the belt are leveled in the interval between the maximum and minimum acceptable values.

τ ₁ is the time after the preliminary heating of the weld zone, through which the temperature on the outer and inner side of the beam belt and the temperature in the wall of the beam at the point of contact with the belt is reduced to the maximum allowable, τ ₂ is the time after the preliminary heating of the weld zone, through which the temperature on the outer and inner sides of the beam belt and the temperature in the beam wall at the point of contact with the belt is reduced to the minimum allowable. The interval between the maximum and minimum allowable temperature values depends on the cross section of the beam, the thickness of the weld and the power of the heating device. After the suture is applied, immediately (without allowing the welding zone to cool), the beam is turned over and the seam is welded on the other side of the wall, i.e. one belt is completely welded, and then the second belt is welded in the same order.

The stand for welding beams contains supports 1 with inclined support elements 2, on which are mounted stops 3 for mounting the beams 4 assembled on tack welds, a device 5 for welding seams between the wall 6 and the belt 7 of the beam 4, a mechanized heating device 8, which produces heating from the outside side of the belt 7 using the heater 9, the device 10 for entry onto the beam 4 and the device 11 for exit from the beam 4, the device 12 for lifting, transporting and turning over the welded beams. As the device 5 for welding, a conventional welding machine can be used. As a mechanized heating device 8, various technical solutions can be used. For example, the device itself can be located on the outside of the belt 7 of the beam and move along the rails in a given direction. However, it is recommended for this purpose to use a modernized version of the device for dressing mushrooms (AS No. 580027), which for many years has justified itself in practice.

The proposed mechanized heating device 8 consists of a housing 13 with support rollers 14 mounted on the wall 6 of the beam to be welded, a pressure roller 15 resting on the belt 7 of the beam to be welded, a rocker arm 16, an envelope belt attached to the body at one point in height by means of a hinge 17 and connected to the housing 13 at another point in height by a tension spring 18, and a heater 9. In the housing 13 there is an electric motor with a gearbox and a system for adjusting the speed of movement. The electric motor through a gearbox is connected to the support rollers and ensures that the heating device is moved by them. The beam 16 from the outer side of the beam belt is equipped with a stop system 19 containing thrust rollers directly abutting the beam belt 7 under the action of the spring 18. An adjustment device is mounted on the beam 16 for adjusting the position of the heater 9 along the height of the belt 7 relative to the wall 6. It contains a guide rod 20, on which the heater 9 is fixed using the locking screw 21.

Figure 1 also shows the following notation: position 22 denotes gas hoses for the burner of heater 9, positions 23 and 24 indicate the supply wires for heating 8 and welding devices 5, position 25 denotes the path of the gas burner nozzle, the letter “S” denotes the distance between the heating 8 and welding 5 devices, the letter "V" - the speed of the heating device 8, the letter "β" - the angular deformation of the belt of the beam after the passage of the mechanized heating device, the letter "b" - width TVOC heating during movement path 25 of the burner nozzle.

In figure 2, the letters P ₁ , P ₂ , P ₃ , P ₄ and P _x denote the forces arising in the system "beam - mechanized heating device" after the actuation of the spring 18.

In figure 3, points A and B are located along the axis of the beam wall, respectively, on the outer and inner surfaces of the beam belt 7, point C, in the beam wall 6, at a distance of 30 mm from the inner surface of the belt 7.

Figure 4 shows the heating temperature t _A , t _B , t _C on the vertical axis (respectively, at points A, B, C in figure 3), on the horizontal axis, the time in minutes from the moment the burner nozzle passes through the calculated section. The positions τ _g , τ ₁ , τ ₂ denote respectively the time of maximum heating at point A, the maximum and minimum allowable heating at points B and C. The positions t _max , t _min , Δt _g denote the maximum and minimum allowable heating temperatures at points B and C , the temperature difference between points A and B at the time τ _g .

The proposed method of manufacturing beams changes the order of preheating of the weld overlay zone, since heating is performed from the outside of the belt, and not from the inside, as usual. At the time of the weld seam of the metal temperature (see Figs. 3 and 4) at point A (on the outside of the belt 7), point B (on the inside of the belt 7) and at point C (in the wall 6 at a distance of about 30 mm from the inner surface of the belt 7) should be approximately equal and be in the interval between the maximum (t _max ) and minimum (t _min ) values allowed by the current technical conditions. If we consider separately any cross section along the length of the beam (Fig. 3) and take as “0” the point in time at which the burner nozzle passes this section, then the nature of the temperature change in time at points A, B and C (respectively, temperature _A , t _B and t _C ) is shown in Fig.4. At the moment τ _g , i.e. when maximum heating is reached at point A, residual plastic deformations are formed due to the temperature difference Δt _g , which, after equalization of temperatures along the cross section of the belt 7, leads to the formation of residual angular deformations "β" (Fig. 1). After applying the weld, the deformations “β” are eliminated (within the tolerance), so that there are no residual deformations of the mushroom shape.

The gain in this case is determined by two points. Firstly, the heat input when creating a preliminary bend "β" is less than when editing mushrooms of the same magnitude (see figure 5). Figure 5 shows the dependence of the coefficient "K" on the speed of movement of the burner along the element to create deformation of the mushroom. After heating the test element, the angular strain value β was measured. Heating was carried out for different steels and sheet thicknesses. Coefficient "K" shows the ratio of the angular deformations of the free sheet and the sheet with a welded wall (ie brand). To obtain "K", a series of pair heating was carried out for the same burner speed (free sheet and brands). The power of the burner was assumed to be approximately 3200 cal / s (i.e., usually used for these purposes). From the graphs in figure 5 it is seen that in a free sheet the angular deformation "β" is up to two times easier to obtain than in the brand. Secondly, heat input for pre-bending is used simultaneously for pre-heating (i.e. it is not inserted twice).

As the heating device 8 moves away from the calculated cross-section by a distance “S”, the temperatures at points A, B, C begin to equalize. The welding device 5 can perform welding in the time interval Δτ = τ ₂ -τ ₁ when these temperatures are below t _max and above t _min .

The values of τ ₁ , τ ₂ and other parameters are determined by calculation depending on the size of the cross section, the thickness of the welds, the power of the heater, etc.

To test the method, the beam was welded under experimental conditions.

Beam 4 was assembled at the assembly stand. Belts 7 to wall 6 were attached using short welds - “tacks”. Next, the assembled beam using the device 12 for lifting, transporting and turning over the welded beams was installed on a stand for welding beams, placing the beam on the inclined support elements 2, while the beam was kept from sliding down due to the stops 3. Next, the entrance 10 and exit were installed to the beam 11. Warming up by device 8 and welding by device 5 was carried out sequentially with a certain gap “S”, determined by calculation. After the suture was applied, immediately (without allowing the welding zone to cool), the beam was cut over and the seam was welded on the other side of the wall, i.e. one belt was completely welded, and then the second belt was welded in the same order.

A mechanized heating device was installed by supporting rollers 14 on the wall 6 of the beam to be welded. At the time of installation, the clamping spring 18 was loosened or removed, which allowed the beam arm 16 to be freely installed. The power of the spring 18 was selected so that, with the tilted position of the beam being welded, the thrust system 19 was pressed against the belt 7, i.e. the compressive force P ₂ should be greater than the “tearing off” component P _x arising from the weight of the hinged part of the device (connected to the beam 16) and the force of action of the gas hoses 22 and wires 23. Thus, the tensile force P ₁ in the spring 18 should be such so that the forces P ₂ , P ₃ , P ₄ pressing against the wall 6 and the belt 7 are such that the stability of the position of the heating device 8 relative to the beam being welded 4 is ensured, while the nozzle of the heater 9 will always exactly repeat the position of the axis of the wall 6 when moving, in spite I am on always existing deviations of the axis of the wall from the axis of the belt. This is very important, since when the center of the nozzle deviates from the axis of the wall, there will be asymmetric heating, leading to the formation of distortions of the skew of the belt relative to the wall.

Thus, after the assembly of the T-element at electric grippers, the strip was heated with a GDU burner. Since the belt of the beam is not rigidly fixed to the wall, heating the strip on the belt causes a sufficiently large residual angular deformation. In our case, for a belt sheet with a thickness of 16 mm (steel grade 10HSNDA), the width of the heating strip was 50 mm, and the maximum heating temperature was 750 ° C. The residual angular strain was β = -1.6%. Then the first fillet weld was welded using standard technology: semi-automatic welding in a mixture of protective gases (I _st = 160-180 A, U _st = 25-26 B, weld leg 8 mm). Angular deformation became equal to β = -0.59%. After welding the second fillet weld β = 0.1%. As can be seen, after welding two fillet welds, the beam belt from negative angular deformation turned into positive, and it is within the tolerance for residual deformation of mushroom shape.

The values of S, τ ₁ and τ ₂ were respectively 4.3 m, 5 min, 17 min.

Using the proposed method for manufacturing welded beams, a gain in two directions is achieved.

Firstly, during the welding process, one of the three technological operations is eliminated. Usually, three operations are performed: pre-heating the welding zone, welding and dressing of residual deformations of mushroom shape. In the proposed method, preheating is done according to a different scheme, which allows you to create a preliminary bending of the belt. After welding, there is either no residual deformation of the mushroom, or they are within the tolerance.

Secondly, it is possible to reduce the total energy consumption, if before editing the mushroom shape was carried out thermally. If dressing of mushrooms was carried out in a cold way, then this method allows you to eliminate entire sections of workshops with equipment for cold dressing.

Claims (2)

1. A method of manufacturing a welded beam, including the assembly of the belt and the wall of the beam at the tacks, preheating the zone of the weld before welding and welding, characterized in that the preheating of the zone of the weld before welding is carried out on the outside of the belt opposite the wall of the beam by a heating device with the formation of a preliminary bending with negative angular deformations, and welding is performed by a welding device, which is arranged in series with the heating at a distance from it, at which Res interval Δτ = τ ₂ -τ _1, the temperature on the outer and inner sides of the beam waist and the temperature in the wall of the beam at the point of abutment to the belt and aligned in a range between the maximum and minimum permissible values, depending on the cross-section of the beam, the weld thickness and the power of the heating device, where τ ₁ is the time after the preliminary heating of the weld zone, through which the temperature on the outer and inner sides of the beam belt and the temperature in the wall of the beam at the point of contact to the belt is reduced to the maximum allowable, τ ₂ is the time after the preliminary heating of the weld zone, through which the temperature on the outer and inner sides of the beam belt and the temperature in the wall of the beam at the point of contact with the belt is reduced to the minimum allowable, while after the seam is applied on one side of the wall, the beam is immediately turned over and a seam is welded on the other side of the wall, completely welding the belt. 2. The method according to claim 1, characterized in that the welding device is located at a distance from the heating, in which the time τ ₁ is 3 minutes, and the time interval Δτ is 20 minutes

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