What is Cryogenic Liquid Cylinder Welding Machine

Preparation before welding

Equipment inspection:

First, check the appearance of the welding machine to ensure that the equipment has no obvious damage or deformation. Check whether the power cord and control line of the welding machine are well connected, and whether the plug is loose or damaged to avoid equipment failure or safety accidents caused by electrical connection problems.

Check the welding power supply of the welding machine, turn on the power switch, and observe whether the power indicator light is on normally. Check whether the ammeter, voltmeter and other instruments can work normally and whether the displayed values are accurate. At the same time, check the cooling system of the welding machine to ensure that the coolant level is normal and the cooling fan can operate normally to prevent the equipment from overheating during welding.

Workpiece preparation:

Clean the low-temperature cylinder workpiece to be welded to remove impurities such as oil, rust, dust, etc. on the surface. You can use a special cleaning agent or sandpaper to clean it to ensure that the surface of the welding part is smooth. For stainless steel cylinders, be careful to avoid using cleaning agents containing chloride ions to prevent corrosion.

Check whether the size and shape of the workpiece meet the welding requirements. If splicing welding is required, ensure the dimensional accuracy of the splicing parts. The splicing gap should generally be controlled within an appropriate range. For example, for argon arc welding, the gap is usually between 0.5-2mm to ensure welding quality.

Welding materials and gas preparation:

Choose appropriate welding materials, such as welding wire, according to the material of the cryogenic cylinder. For stainless steel cylinders, stainless steel welding wire with a chemical composition similar to that of the parent material is generally selected; for aluminum alloy cylinders, corresponding aluminum alloy welding wire is selected. Check the quality of the welding wire to ensure that the surface of the welding wire is smooth and free of defects such as oil stains and oxidation.

Prepare shielding gas, such as argon. Check whether the pressure of the argon gas cylinder is sufficient. Generally, the pressure of the gas cylinder is required to be between 1 and 10 MPa. Connect the gas delivery pipeline and ensure that there is no leakage in the pipeline. Adjust the gas flow regulator and set the appropriate gas flow according to the welding process requirements. For example, in argon arc welding, the gas flow is generally between 8 and 15 L/min.

Fixture installation and workpiece positioning:

Select the appropriate welding fixture to firmly fix the workpiece on the welding table. The choice of fixture should be based on the shape and size of the workpiece to ensure that it can provide stable support and positioning. For example, for a cylindrical cylinder, a V-clamp or a ring clamp can be used for fixing.

Position the workpiece accurately to ensure that the welding part is in the right position. Use measuring tools (such as calipers, angle rulers, etc.) to check whether the position and angle of the welding joint meet the welding process requirements to ensure the accuracy of welding.

Welding process operation

Parameter settings:

Set the welding parameters on the control panel of the welding machine according to the welding process and factors such as workpiece material and thickness. For argon arc welding, mainly set the welding current, voltage, welding speed and other parameters. The welding current is generally determined according to the thickness of the workpiece. For example, when welding 3mm thick stainless steel, the current can be set between 100-120A; the voltage is usually between 10-20V; the welding speed is determined according to the weld length and the required welding efficiency, generally between 5-15cm/min.

Set the pre-gas supply time and post-gas shut-off time of the shielding gas. The pre-gas supply time is generally between 2 and 5 seconds to ensure that the welding area is fully covered by the shielding gas before welding begins; the post-gas shut-off time is between 3 and 8 seconds to prevent the high-temperature weld from being oxidized by air after welding.

Arc striking operation:

For non-automatic welding machines, use a suitable arc starting method. For example, in argon arc welding, high-frequency arc starting or contact arc starting can be used. When operating with high-frequency arc starting, aim the welding gun at the welding part, press the arc starting button, and use high frequency and high voltage to generate an arc between the tungsten electrode and the workpiece; contact arc starting is to gently touch the tungsten electrode to the surface of the workpiece, and then quickly lift it a certain distance to generate an arc. During the arc starting process, pay attention to maintaining the distance and angle between the tungsten electrode and the workpiece. The distance is generally between 2-4mm, and the angle is between 70-90 degrees according to the welding position and process requirements.

Welding Operation:

After the arc is successfully struck, welding is performed according to the preset welding speed and welding path. For straight welds, the welding machine's automatic travel device or manual uniform speed movement of the welding gun can be used; for circular welds or welds of complex shapes, the operator needs to skillfully control the movement direction and speed of the welding gun to ensure uniform welds. During the welding process, the welding gun should be kept stable to avoid shaking, and attention should be paid to observing the formation of the weld, such as weld width, penetration depth, and molten pool state.

Pay attention to the wire feeding operation during welding (if it is consumable electrode welding). Control the wire feeding speed according to the welding current and weld filling requirements. The wire feeding speed should match the welding speed, which is generally controlled by adjusting the wire feeding wheel speed of the wire feeder. For example, when welding aluminum alloy liquid cylinders, the wire feeding speed may be between 3-8m/min.

Arc closing operation:

When welding is nearly completed, the correct arc extinguishing operation should be performed. For argon arc welding, the arc extinguishing method can be adopted, that is, the welding current is gradually reduced to allow the molten pool to slowly cool and solidify, avoiding defects such as arc pits and shrinkage holes. After the arc is extinguished, the shielding gas is kept supplied for a period of time to ensure that the weld is not oxidized during the cooling process.

Post-welding inspection and cleaning

Weld visual inspection:

After welding is completed, first conduct an appearance inspection of the weld. Observe the surface quality of the weld, check whether the weld is uniform in width and whether the surface is smooth and flat, and whether there are defects such as undercuts, weld bumps, pores, cracks, etc. The allowable deviation of the weld width is generally around ±1mm, and the weld excess height should meet the welding process requirements. For example, for the weld of a low-temperature liquid cylinder that bears pressure, the excess height is generally controlled between 1 and 3mm.

Non-destructive testing (optional):

According to the use requirements and quality standards of cryogenic cylinders, non-destructive testing can be performed. For example, ultrasonic testing, radiographic testing and other methods can be used to check the internal quality of the weld to detect whether there are defects such as lack of fusion, slag inclusions, cracks, etc. in the weld. Non-destructive testing should be performed in accordance with relevant standards and specifications to ensure the accuracy of the test results.

Cleaning and maintenance:

Clean up the welding site and clean up the spatter and residues generated during welding. Turn off the power of the welding machine, cut off the gas source, and organize the welding equipment and tools. Perform simple maintenance on the welding machine, such as cleaning the surface of the welding machine and checking the wear of the equipment, to prepare for the next welding.

If you want to know the operation process of the low temperature Cryogenic Liquid Cylinder Circumferential and Corner Welding Machine, you can consult our customer service staff, we will serve you wholeheartedly 24 hours a day!