Contact welding is necessary for the connection of aluminum and copper wires and steel pipes. Work is performed using a welding machine. It can be purchased or manufactured by yourself. The second option requires less investment.
Types of resistance welding.
Features of the device
Resistance welding is used in the production process of welded joints and large metal parts of the same type. During welding, the metal is heated under the influence of current. The path is non-uniform. At home, such work will require powerful power sources. A small homemade device requires a power of 1000 A. The parameters of contact welding are electric current, force of compression of parts and time of current flow. Adjusting the values of the parameters allows the welding of metal in soft and hard modes.
Scheme of the characteristics of resistance welding.
There are seam, point and butt processing of parts. The high-current current of the electrodes is pressed with the help of conductive. The current passes through a large number of channels in the workpiece. They heat up, helping to melt the center point. In the seam processing using electrodes in the form of rollers, which are moving along the seam. Processing the butt method requires passing through the junction of parts with the same current cross section, and after heating a precipitate is performed.
Processing of parts performed by the method of one of 2 types of flashing, or resistance. With continuous flashing, the parts fastened by the clamps come into contact when the mobile clamp moves when current is applied. The welded ends of the products are melted. Then the draft is performed at the desired value. The current supply is stopped. The method is used for welding rails, thin-walled pipes and metal sheets. Processing of different types of metal is allowed. The advantage of the method is high performance. The disadvantage is the loss of the processed material due to carbon loss and splashing.Back to table of contents
Scheme of seam welding.
In the intermittent method current is applied. The tight and loose contact of the surfaces to be joined alternates. Then the melting and sediment are performed. The method is used to treat low-carbon steel, if the device is not powerful enough to conduct a continuous-type reflow. Heating is performed by the method of resistance due to the additional cost of the metal. The current is switched on with a closed circuit, and then the parts are bred, melted and precipitated.
When the resistance parts of contact welding tightly pressed to each other. Serves current. It is turned off after heating the connected elements to a plastic state and carrying out precipitation.
The electrical circuit of the spot welding machine.
The method is used to process:
- parts of low carbon steel with a round or rectangular section of no more than 1000 sq. mm;
- surfaces of alloyed steel with an area of not more than 21 sq. mm;
- non-ferrous metals, their alloys;
- dissimilar metals (mixed steel).
Features of the method - the elements to be connected must be clean, it is required to control the temperature of heating.Back to table of contents
The equipment that is used for resistance welding can be suspended, mobile and stationary. The device allows you to connect metal parts with a thickness of 0.08-0.9 mm, consuming a lot of electricity.
Table of parameters for resistance welding.
The central elements of the welding machine are represented in the form of a pistol and a power unit. The last element is made of relay and transformer. The electrode is connected to the 1st winding with a cable. Another conclusion will be in the process of welding to connect with the treated metal surface. The gun is assembled from 2 elements. Their shape and size should be the same. For isolation use getinaks or textolite. For self-production of the device in question you will need:
- Power Supply;
Electrical circuit of spot welding.
In the front is a lamp holder, a small switch and an adapter, and in the back is a light switch. Screws are used to connect linings. The welding cable is connected to the adapter.
The device is assembled, taking into account the parameters of the power supply. They depend on the dimensions of the transformer used. Experts advise to pre-assemble the last unit, in which the cross section of the magnetic wire should reach more than 60 sq. Mm.
The transformer is located on one side of the magnetic wire. Insulator - wedges of wood. Bending 2 winding is performed using loops. The welding cable is fixed with special bolts. Electrical tape or fluoroplastic is used to isolate layers of the 1st winding, fixed with tape. Magnetic wire angles and bolts M8. The screed is needed to straighten the plate. The frame is fixed with wedges of wood.Back to table of contents
To check the functioning of the transformer, you need to turn on the device in a network of 220 V, measuring the voltage of the 2nd winding.
Relief welding scheme.
The indicator should reach 41 V. Then calculate the parameters of the base. The auxiliary transformer provides a voltage of 6-15 W on the 2nd winding. The device is made of magnetic wire with a cross section of 1 sq. Cm. The windings between the wires are insulated. The manufacture of a self-made welding machine involves the installation of a gun. Pre-made electrode and adapter. In the holder for the lamp, the channels for the wire that will lead to the lamp are made.
The microswitch is attached to the covers with cogs and 2 holders. Material for slats - plexiglass. It is necessary to consider the location of the cable passing through the handle. Trims fasten cogs. The end of the cable must be soldered and inserted into the adapter, fixing the screw. Reliability of fastening lining attached by applying a layer of mastic. The manufacture of the apparatus according to the rules ensures its fast operation.
Holes with a diameter of 0.5-0.8 mm are formed at the welding points of the strip. Including capacitors in series and in parallel, you can test. The finished equipment is connected to the network, the connected surfaces are applied to each other and pressed by the electrode. It must be removed from the treated point 1-1.5 s after switching on. The master using the equipment must wear rubber gloves, goggles and stand on a rubberized mat.
Transformer assembly requires checking the quality of the connection in order to reduce losses due to contact resistance. The reasons for the breakdown of the homemade device are as follows:
- moisture ingress;
- mechanical damage;
- prolonged exposure to vibrations.
Reliable wires of windings protect the device from overheating. Cooling is provided by blowing air, for this, gaps are left in the windings. The 1st layer is wound, slats are installed from the outside. The latter are inserted through every 2nd layer of wire.
The transformer must be blown by a fan, or air must be circulated through the slots. Strong airflow will not be able to reduce the heating of the instrument if it has closed windings. Experts recommend in this case to provide a moderate mode of operation of the equipment.