How to solve the problem of insufficient weld strength in automatic tube welding machines?

1. Welding parameter adjustment
1. Current and voltage
Inspection and calibration: First, use welding parameter monitoring equipment (if available) or a multimeter to check whether the actual output welding current and voltage are consistent with the set value. If it is found that the actual value deviates greatly from the set value, it may be a problem with the welding power supply, and the welding power supply needs to be calibrated or repaired.
Reasonable adjustment: For the case of insufficient weld strength, appropriately increase the welding current and voltage (within the range allowed by the material). Increasing the current can increase the welding heat input, make the weld metal and the parent material better fuse, increase the weld penetration, and thus improve the strength. However, be careful to avoid problems such as excessive current and voltage causing weld burn-through and excessive spatter. The optimal current and voltage parameters can be determined by trial welding, and the amplitude of each adjustment should not be too large. For example, the current can be increased by 5-10A each time for testing.
2. Welding speed
Speed ​​detection: Determine the actual welding speed by observing the welding process or using a speed measurement tool. If the welding speed is too fast, the weld metal will not be fully filled in time, the penetration will become shallow, and the weld strength will be reduced.
Speed ​​adjustment: Appropriately reduce the welding speed so that the weld metal has enough time to fuse with the parent material to ensure the penetration and filling amount of the weld. When adjusting the welding speed, production efficiency and welding quality should be considered comprehensively to avoid problems such as overheating and excessive deformation of the weld caused by too slow speed. Generally speaking, the extent of welding speed reduction can be adjusted according to the actual situation of the weld and the welding process requirements, such as reducing 10% - 20% from the original millimeters per minute for trial welding.
3. Wire feeding speed (for consumable electrode welding)
Wire feeding inspection: Check whether the wire feeding system is working properly, including components such as wire feeding motor, wire feeding wheel, wire feeding tube and conductive nozzle. Ensure that the welding wire can be fed smoothly and stably, and the wire feeding speed is uniform. It can be checked by observing the feeding of the welding wire or using professional wire feeding speed detection equipment.
Speed ​​optimization: If the insufficient strength of the weld is caused by insufficient filler metal, increase the wire feeding speed appropriately. Increasing the wire feeding speed can provide more filler metal for the weld, make the weld fuller, and help improve the strength of the weld. But at the same time, attention should be paid to the matching of wire feeding speed with welding current, voltage and welding speed to avoid defects such as lack of fusion and pores.
2. Weldment preparation
1. Surface cleaning
Cleaning range: Thoroughly clean the oil, rust, scale, moisture and other impurities in the welded parts. These impurities will enter the weld during the welding process, forming defects such as slag inclusions and pores, reducing the strength of the weld.
Cleaning method: For oil stains, organic solvents (such as acetone, alcohol, etc.) can be used for wiping; for rust and scale, mechanical grinding (such as sandpaper, grinding wheel, etc.), chemical pickling or sandblasting can be used for treatment. Before welding, ensure that the surface of the weldment shows metallic luster to ensure good fusion of the weld and the parent material.
2. Groove design and processing
Groove form selection: According to the thickness, material and welding requirements of the pipe, select the appropriate groove form, such as V-type, U-type, double V-type, etc. The appropriate groove form can increase the fusion area of ​​the weld and improve the strength of the weld. For example, for thicker pipes, a U-shaped groove can obtain a larger fusion area and better weld root quality than a V-shaped groove.
Groove size control: Accurately process parameters such as groove angle, blunt edge size and root gap. Too small a groove angle will result in poor weld fusion, and too large a root gap may cause excessive weld filler metal, which is prone to welding defects. After processing the groove, it is necessary to check and measure to ensure that the groove size meets the welding process requirements.
III. Welding material inspection
1. Welding wire quality
Quality verification: Check whether the material of the welding wire matches the weldment, including the chemical composition and mechanical properties of the welding wire. Using welding wire that does not meet the requirements will result in weld strength that does not meet the standards. At the same time, check the surface quality of the welding wire, which should be free of defects such as oil stains, rust, oxidation, etc., and the welding wire diameter should meet the specified requirements.
Welding wire replacement: If problems are found in the quality of the welding wire, such as inconsistent materials and obvious defects, qualified welding wire should be replaced in time. After replacing the welding wire, it may be necessary to readjust the welding parameters to ensure welding quality.
2. Shielding gas (if it is gas shielded welding)
Gas purity check: Use gas analyzer and other equipment to check the purity of shielding gas. If the shielding gas purity is insufficient, such as containing too much oxygen, water vapor and other impurities, it will cause the weld metal to oxidize, produce defects such as pores, and reduce the strength of the weld.
Gas flow adjustment: Ensure that the shielding gas flow is appropriate. If the flow is too small, it cannot effectively protect the molten pool, and the weld will be susceptible to air intrusion and produce pores; if the flow is too large, it may cause turbulence, and air will be drawn into the molten pool, which will also affect the quality of the weld. According to the welding process requirements and the actual welding situation, adjust the shielding gas flow. Generally, it can be adjusted within the range of 10-20L/min, and the optimal flow can be determined by trial welding.
IV. Equipment inspection and maintenance
1. Welding head and conductive nozzle
Check the welding head accuracy: Check the rotation accuracy and axial movement accuracy of the welding head. If the welding head movement is not accurate, it will cause poor weld formation and affect the weld strength. Check and maintain the mechanical parts of the welding head, such as cleaning and lubricating the guide rails and rotating parts, tightening loose screws, etc.
Replace the conductive nozzle: The conductive nozzle is a key component that affects the transmission of welding current. If the conductive nozzle is severely worn, it will increase resistance, cause unstable welding current, and affect the quality of weld fusion. Check the wear of the conductive nozzle regularly. When the inner diameter of the conductive nozzle is worn beyond a certain limit (such as 1.2-1.5 times the original inner diameter) or blocked, it should be replaced in time.
2. Overall performance maintenance of the equipment
Electrical system inspection: Conduct a comprehensive inspection of the electrical system of the automatic tube welding machine, including welding power supply, controller, sensor and other components. Check whether the electrical components are damaged, overheated, poor contact, etc., to ensure that the electrical system can stably provide the energy and control signals required for welding. For electrical problems found, repair or replace components in time.
Mechanical transmission system maintenance: Check the mechanical transmission system of the equipment, such as motors, reducers, screws, chains and other components. Ensure that the mechanical components can operate smoothly and accurately to provide reliable power and precision for the movement of the welding head. Regularly lubricate, tighten and inspect mechanical transmission components to eliminate potential faults in a timely manner.