Resistance Welding Machine Use And Safety
The resistance welding machine is to press the workpiece to be pressed between the two electrodes, and impose a current, the use of current flowing through the workpiece contact surface and the adjacent area of the thermal resistance generated by heating to the molten or plastic state, so that the formation of metal-bonded a way.
First, the use of resistance welding machine conditions
1, the natural cooling of the air welding machine, the altitude of not more than 1000m, the maximum ambient air temperature is not greater than 40 ℃.
2, water cooling of the welder, the water temperature of the inlet is not greater than 30 ℃, the cooling water pressure should be able to ensure that the necessary flow, water quality should meet the industrial water standards.
3, power supply parameters: 220V or 380V, 50Hz. The welder should be able to function properly under the following grid power quality conditions:
Voltage fluctuation: within ± 10% (when frequency is rated).
Frequency fluctuation: no more than ± 2% (when voltage is rated).
Second, the installation of resistance welding machine
1, the welding machine should be away from the equipment with intense vibration, such as large tonnage presses, air compressors, etc., so as not to cause control equipment work disorders.
2, gas pressure requirements and stability. Compressed air pressure shall not be less than 0.5MPa, if necessary, should be placed in the vicinity of the welding tank.
3, the cooling water pressure should generally not less than 0.15MPa, water temperature is not higher than 30 ℃. Requires pure water quality to reduce leakage or cause pipe clogging. In places where multiple welders are operated, a special cooling water circulation system should be provided when the water pressure is too low or unstable.
4, in the flash butt welding or spot welding, seam welding with the workpiece, there should be ventilation equipment.
Third, the resistance welding machine debugging
1, before the power test
Check whether the insulation of the fuselage is in accordance with the requirements; check whether the grounding of the fuselage is reliable; whether the water and gas are smooth; measure whether the grid voltage matches the nameplate data of the welder.
2, power check
Mainly to check the control device each button and switch operation is normal.
And then run through the welding current under the mechanical action. That is, pull out the voltage level adjustment group handle or the control device on the welding current on / off switch on the open position. Start welding machine, check the working procedures and pressure process.
3, the choice of welding parameters
Use the same material and thickness of the workpiece cut the test pieces for welding. During the test, by adjusting the welding parameters (electrode pressure, secondary no-load voltage, energization time, heat regulation, welding speed, workpiece extension length, burnt amount, forging, burning speed, uplift speed, To obtain the required welding quality.
For the welding of the general workpiece, with a certain number of pieces of welding, the visual inspection should be no deep indentation, cracks and burning. And then by tearing test to check the welding core diameter qualified and uniform can be a few welding parts. After the product quality inspection qualified, welding machine can be put into production use.
On the aviation and aerospace and other demanding workpieces, when the welding machine installation, commissioning qualified, should also be in accordance with the relevant technical standards, welding a certain number of specimens by visual, metallographic analysis, X-ray inspection, mechanical strength measurement and other tests to Evaluate the reliability of the welding machine.
Fourth, the resistance welding machine maintenance
1, daily maintenance
Keep the welding machine clean; the electrical part to keep dry; pay attention to observe the cooling water circulation; check the various parts of the circuit contact and insulation.
2, regular maintenance check
Mechanical parts should be regularly added lubricants. Welding machine should also be in the rotation of the conductive part of the regular special grease; check the active part of the gap; observe the electrode and electrode grip between the normal, with or without leakage; electromagnetic valve work is reliable; water and gas Whether the pipeline has been clogged; whether the electrical contact has been loose; whether the knobs in the control equipment are slipping or not.
Fifth, resistance welding safety
Resistance welding machine secondary voltage is very low, will not produce electric shock hazard. But a voltage for the high voltage, especially the use of a class of capacitor discharge, the voltage can be higher than kilovolt. Thyristors are generally with water cooling, water column charged, so the welding machine must be reliable grounding. The high voltage section in the service control box must be switched off. Capacitive discharge type welding machine, such as the use of high-voltage capacitors, you should install the door switch, open the door automatically cut off the power.
2, anti-crush (bruise)
Resistance welding machine to be fixed one person operation, to prevent more than due to improper with the resulting crush accident. The foot switch must be secure. Foreign on the welding machine on the clamping button with double button type, the operator must be both hands at the same time by a button to clamp to prevent the folder folder event. Multi-spot welding machine in the surrounding fence, the operator must be withdrawn after feeding, from the equipment after a certain distance or close the door before starting welding machine to ensure that moving parts will not be injured.
Resistance welding work often occurs when splashing, especially flash welding, sparks such as fireworks for several seconds to more than ten seconds. Therefore, the operator should wear protective clothing, wear protective glasses, to prevent burns. In the flash area around the brass protective cover is appropriate to cover, to reduce the spark splash. Flash sparks can fly 9 ~ 10m high, so the surrounding and above should be no flammable materials.
Resistance welding welding plating plate, resulting in toxic zinc, lead dust, flash welding a large number of metal vapor generated when grinding electrode with metal dust, which cadmium copper and beryllium cobalt copper electrode in the cadmium and beryllium are great Toxic, and therefore must use a certain ventilation measures.