CN102773590B - Small-section square girder and welding process thereof - Google Patents

Abstract

The invention discloses a square girder with a small cross-section and a welding process thereof, which belongs to the welding technology and solves the problems of small welding space and low welding quality in the prior manual welding. The small cross-section square girder is composed of four beam plates with a width of 200-220mm and a length of ≤10m to form a box-shaped inner cavity. The inner cavity is equipped with a rib plate, and flanges are welded at both ends of the beam plate. , There are internal and external fillet welds between the beam plate and the flange. When welding, first clean up the parts to be welded before welding, install the arc starting plate and the arc receiving plate, and use an automatic welding trolley to carry out welding. Cavity and exposed welds are welded alternately, the inner cavity and exposed welds are welded first, the backside is strictly cleaned, and then the exposed welds are welded, and then the inner cavity and exposed welds are welded sequentially. welding method. The invention controls the welding deformation within the allowable range, improves the torsion resistance and shear resistance of the small-section square girder, and ensures the stability and reliability of the girder.

Description

A small cross-section square girder and its welding process

technical field

The invention belongs to the welding technology, and relates to a square girder with a small cross-section and a welding process thereof.

Background technique

At present, in the coal washing and coal preparation of coal mining machinery, house construction, bridges, lifting equipment and other industries, the small cross-section square girder structure design is widely used, and its stability, reliability and work efficiency during operation are very important.

The girder structure design usually adopts the welded structure design. The internal and external distribution of the weld seam often bears instantaneous impact and alternating load in the working state, and the stress is complicated, so the welding quality of the product is very high. At present, the welding method commonly used in China is manual CO2 gas shielded welding. When the cross-section of the beam involved is small, the welding operation space is narrow, and it is difficult to ensure the quality of manual welding. The failure and fracture of the girder are often caused by welding quality problems.

In order to solve the problem of small welding space and low welding quality in existing manual welding, it is necessary to develop an automatic welding method to solve the problems of small welding space and difficult welding quality assurance brought about by structural design. The wide application of the design structure provides a reliable guarantee.

Contents of the invention

The invention aims to solve the problem of low welding quality in the small welding space of existing manual welding, and provides a small cross-section square girder and its welding process.

A small cross-section square girder, which is composed of four beam plates with a width of 200-220mm and a length of ≤10m to form a box-shaped inner cavity. The inner cavity is provided with a rib plate, and flanges are welded at both ends of the beam plate. Between the beam and the flange are internal and external fillet welds.

A welding process method for a square girder with a small cross-section, comprising the following steps:

First of all, clean up the parts to be welded before welding, install and weld the arc starting plate and arc receiving plate, and use the automatic welding trolley to carry out welding. During welding, the inner cavity and the exposed weld seam are alternately welded, and the inner cavity is welded first. After the backside is strictly cleaned, the exposed weld seam is welded as the base weld seam, and then the inner cavity and the exposed weld seam are welded in sequence. During the welding process, the welding deformation of the girder is controlled by the segmented back welding method, and the welding trolley is automatically welded during welding. The welding speed is 0.1-5m/min, and the vibration aging stress relief treatment is adopted after the welding is completed.

The welding current is 120~300A, the arc voltage is 22~33V, the wire feeding speed is 1~15m/min, and the mixed gas 80%Ar+20% _CO2 is used in the welding process.

The welding current is 250~280A, the arc voltage is 27~31V, the wire feeding speed is 1~15m/min, and the mixed gas 80%Ar+20% _CO2 is used in the welding process.

The small cross-section square girder of the present invention is a box-shaped structure with small cross-sectional area, long longitudinal length, weak support and large welding volume. The welding process mainly solves the fracture of the small cross-section square girder, weld cracking and long-term action under alternating loads. Problems such as low stress brittle fracture generated under the environment. Using the welding process method of the present invention can not only ensure the welding quality of small-section square girders (welding joint grade I, GB/T3323-2005 or GB/T11345-1989), control the welding deformation within the allowable range, but also improve the welding quality of small-section beams. The torsion and shear resistance of the square girder ensures the stability and reliability of the girder.

Description of drawings

Fig. 1 is a structural representation of the present invention;

In the figure: 1-beam plate, 2-rib plate.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, a square girder with a small cross-section consists of four beam plates with a width of 220mm and a length of 10m in pairs to form a box-shaped inner cavity, and a rib plate 2 is arranged in the inner cavity, and two ends of the beam plate 1 are welded. Flanges, where the beam-slab and the beam-slab and the flange are internal and external fillet welds.

When soldering, the following steps are involved:

1. Before welding, clean up the oil, dirt, scale, etc. in the 30mm area on both sides of the weld;

2. Install welding arc starting plate and arc closing plate;

3. Use the automatic welding trolley to carry out the bottom welding of the inner cavity boat welding, starting from the arc striking plate to the arc closing plate, the welding seam height is 5~6mm, and welding is performed in diagonal order during welding; the diameter of the welding wire is φ1 .2; welding current 250~260A; arc voltage 27~29V; gas flow 15~20L/min; welding speed 450mm/min;

4. Use an angle grinder to clean the back of the weld in turn, clean up the part that is not penetrated, so that the part to be welded is flat, smooth and free of impurities, and then use an automatic welding trolley, adopt the segmented back welding method, and weld in turn When welding, according to the diagonal order, welding in turn, the welding seam height is 5~6mm; the diameter of the welding wire is φ1.2; the welding current is 260~270A; the arc voltage is 28~30V; the gas flow rate is 15~20L/min ;Welding speed 440mm/min;

5. Use the automatic welding trolley to carry out inner cavity boat-shaped welding to the welding seam height required by the process, starting from the arc starting plate to the arc receiving plate to close the arc. The welding seam height is 5~6mm per layer. When welding, follow the diagonal order, in order Welding; wire diameter φ1.2; welding current 270~280A; arc voltage 29~31V; gas flow 15~20L/min; welding speed 430mm/min;

6. Use a flat shovel and a wire brush to clean the splashes and scales of the four exposed bottom welds, use low-pressure air to blow the welds clean, use an automatic welding trolley, and use the segmented back welding method to weld the welds in sequence To the welding seam height required by the process, when welding, weld according to the diagonal order; among them, the diameter of the welding wire is φ1.2; the welding current is 270~280A; the arc voltage is 29~33V; the gas flow rate is 15~20L/min; the welding speed is 450mm/ min;.

7. Use a torch to cut off the arc starting plate and arc receiving plate, and clean up welding slag and splash;

8. Assembling and welding beam flanges or parts and components;

9. Vibration aging: equipment model LH—KYFSY0070300, exciter eccentricity 40°, exciter speed, acceleration, excitation time (1) 3620rpm, 17m/s ² , 10min; (2) 3950rpm, 21m/s ² , 8min; (3) 4295rpm, 26m/s ² , 8min; (4) 4710rpm, 31m/s ² , 8min; (5) 5040rpm, 37m/s ² , 6min.

Example 2

As shown in Figure 1, a square girder with a small cross-section is composed of four pairs of beam plates with a width of 200mm and a length of 9m to form a box-shaped inner cavity, and a rib plate 2 is arranged in the inner cavity, and the two ends of the beam plate 1 are welded. Flanges, where the beam-slab and the beam-slab and the flange are internal and external fillet welds.

When soldering, the following steps are involved:

1. Before welding, clean up the oil, dirt, scale, etc. in the 25mm area on both sides of the weld;

2. Install welding arc starting plate and arc closing plate;

3. Use the automatic welding trolley to carry out the bottom welding of the inner cavity boat welding, starting from the arc striking plate to the arc closing plate, the welding seam height is 5~6mm, and welding is performed in diagonal order during welding; the diameter of the welding wire is φ1 .2; welding current 120~150A; arc voltage 22~24V; gas flow 15~20L/min; welding speed 450mm/min;

4. Use an angle grinder to clean the back of the weld in turn, clean up the part that is not penetrated, so that the part to be welded is flat, smooth and free of impurities, and then use an automatic welding trolley, adopt the segmented back welding method, and weld in turn When welding, according to the diagonal order, welding in turn, the welding seam height is 5~6mm; the diameter of the welding wire is φ1.2; the welding current is 150~170A; the arc voltage is 23~25V; the gas flow rate is 15~20L/min ;Welding speed 440mm/min;

5. Use the automatic welding trolley to carry out inner cavity boat-shaped welding to the welding seam height required by the process, starting from the arc starting plate to the arc receiving plate to close the arc. The welding seam height is 5~6mm per layer. When welding, follow the diagonal order, in order Welding; welding wire diameter φ1.2; welding current 170~190A; arc voltage 25~27V; gas flow 15~20L/min; welding speed 430mm/min;

6. Use a flat shovel and a wire brush to clean the splashes and scales of the four exposed bottom welds, use low-pressure air to blow the welds clean, use an automatic welding trolley, and use the segmented back welding method to weld the welds in sequence To the welding seam height required by the process, when welding, weld according to the diagonal order; among them, the diameter of the welding wire is φ1.2; the welding current is 170~190A; the arc voltage is 25~27V; the gas flow rate is 15~20L/min; the welding speed is 450mm/ min;.

7. Use a torch to cut off the arc starting plate and arc receiving plate, and clean up welding slag and splash;

8. Assembling and welding beam flanges or parts and components;

9. Vibration aging: equipment model LH—KYFSY0070300, exciter eccentricity 40°, exciter speed, acceleration, excitation time (1) 3620rpm, 17m/s ² , 10min; (2) 3950rpm, 21m/s ² , 8min; (3) 4295rpm, 26m/s ² , 8min; (4) 4710rpm, 31m/s ² , 8min; (5) 5040rpm, 37m/s ² , 6min.

Claims (1)

1. A welding process for a small cross-section square girder, characterized in that: the small cross-section square girder is composed of four beam plates (1) with a width of 200-220 mm and a length of ≤ 10 m to form a box-shaped inner cavity. There are ribbed plates (2) in the cavity, and flanges are welded at both ends of the beam plate (1), and the inner and outer fillet welds are used between the beam plate and between the beam plate and the flange; the specific welding process includes the following Steps: First, clean up the parts to be welded before welding, install the arc striking plate and the arc receiving plate, and use the automatic welding trolley to carry out welding. During welding, the inner cavity and the exposed weld seam are alternately welded, and the inner cavity is welded first. Weld the weld seam. After the back is strictly cleaned, the exposed weld seam is welded as the bottom weld seam, and then the inner cavity and the exposed weld seam are welded sequentially. The welding speed of the welding trolley is 0.1-5m/min, and after the welding is completed, vibration aging is used to relieve stress; wherein, the welding current is 250-280A, the arc voltage is 27-31V, and the wire feeding speed is 1-15m/min. Use mixed gas 80%Ar+20%CO2; vibration aging: eccentricity of the exciter is 40°, rotational speed, acceleration, and excitation time of the exciter 1) 3620rpm, 17m/s ² , 10min; 2) 3950rpm, 21m/s ² , 8min; 3) 4295rpm, 26m/s ² , 8min; 4) 4710rpm, 31m/s ² , 8min; 5) 5040rpm, 37m/s ² , 6min.