Strainer Filter Mesh Screen Seam Welding Machine

Product Details

The electrode used for seam welding is a round roller, the diameter of the roller is generally 50 to 600 mm, and the commonly used diameter is 180 to 250 mm. The thickness of the roller is 10 to 20 mm, and the contact surface has two types: cylindrical surface and arc surface.

In some cases, a conical surface is used. Cylindrical rollers are widely used for welding various steels and high-temperature alloys. Arc rollers are often used for welding light alloys because they are easy to dissipate heat and have excessively uniform impressions.

The roller usually adopts an external cooling method. When welding non-ferrous metals and stainless steel, clean tap water is sufficient. When welding general steel, in order to prevent rust, the water solution containing 5% borax is commonly used for cooling. The roller is sometimes cooled by internal circulating water, especially the welding machine for welding aluminum alloy, but its structure is much more complicated.

The Process of Seam Welding

The formation of seam welded joints is essentially the same as spot welding, so the factors that affect welding quality are also similar. Mainly include welding current, electrode pressure, welding time, buckle at rest, welding speed and roller diameter.

(1) Welding Current

The source of heat required for seam welding to form a nugget is the same as that for spot welding, which uses the heat generated by the resistance of the welding zone through the use of electric current. Given other conditions, the size of the welding current determines the penetration rate and overlap of the nugget. When welding low carbon steel, the average penetration rate of the nugget is 300o-70% of the thickness of the steel plate, with 45%-50% being the best. In order to obtain the gas-tight weld nugget overlap should not be less than 15%-20%b

When the welding current exceeds a certain value, continuing to increase the current can only increase the penetration rate and overlap of the nugget without increasing the strength of the joint, which is uneconomical. If the current is too large, defects such as deep indentation and weld burn-through will also occur.

During Seam Welding, the nuggets overlap each other and cause a large shunt. Therefore, the welding current is usually increased by 150o ^r40% compared with spot welding.

(2) Electrode Pressure

The influence of electrode pressure on the size of the nugget during seam welding is the same as that of spot welding. Too high electrode pressure will make the indentation too deep, and will accelerate the deformation and wear of the roller. Insufficient pressure will easily produce shrinkage holes, and will easily burn the roller due to excessive contact resistance and shorten its service life.

(3) Welding Time and Rest Time

In seam welding, the size of the nugget is mainly controlled by the welding time, and the overlap amount is controlled by the cooling time. At a lower welding speed, the ratio of welding to resting time is 1. 25:1 ^}2:1, and satisfactory results can be obtained. When the welding speed increases, the distance between the welding points increases. At this time, to obtain welds with the same overlap amount, this ratio must be increased. For this reason, at higher welding speeds, the ratio of welding to rest time should be 3:1 or higher.

(4) Welding Speed

The welding speed is related to the welded metal, the thickness of the plate, and the requirements for the strength and quality of the weld. Usually when welding stainless steel, high-temperature alloys and non-ferrous metals, in order to avoid spatter and obtain a high-density weld, a lower welding speed must be used. Sometimes step seam welding is used, so that the entire process of nugget formation is carried out with the roller stopped. The welding speed of this seam welding is much lower than the commonly used intermittent seam welding.

The welding speed determines the contact area between the roller plate and the plate, as well as the contact time between the roller plate and the heating part, which affects the heating and heat dissipation of the joint. When the welding speed increases, in order to obtain sufficient heat, the welding current must be increased. Excessive welding speed will cause the surface of the board to burn and the electrode adhesion, so even if the external water cooling is used, the welding speed will be limited.