Mechanical Introduction
Spot Welder
Spot Welder according to the use of points, there are universal (general-purpose), special-purpose type; according to the number of simultaneous welding joints points, there are single-point, double-point, multi-point; according to the conductive mode, there are single-side, double-side; in accordance with the drive mode of pressurized mechanism points, there are foot-operated, motor-cam, pneumatic, hydraulic type, Composite (gas-hydraulic combined); according to the characteristics of the operation, there are non-automatic, automatic; according to the installation method, there are fixed, mobile or lightweight (hanging); according to the welding machine's movable electrode (usually the upper electrode) in the direction of movement, there are vertical stroke (electrode for straight-line movement), arc stroke; according to the supply of electricity, there is a frequency welding machine (using 50 Hz AC power supply), Pulse welder (DC pulse welder, discharge welder, etc.), frequency welder (such as low-frequency welder).
When the workpiece and the electrode must be, the resistance of the workpiece depends on its resistivity. Therefore, the resistivity is an important property of the welded material. Resistivity of the metal its conductivity is poor (such as stainless steel) low resistivity of the metal its conductivity is good (such as aluminum alloy). Therefore, spot welding of stainless steel and heat dissipation difficult, spot welding of aluminum alloys and heat dissipation difficult easy. Spot welding, the former can be used with a small current (a few thousand amperes), while the latter must use a large current (tens of thousands of amperes). Resistivity depends not only on the type of metal, but also on the state of heat treatment, processing and temperature of the metal.
The welding time and the welding current can be complementary to each other within certain limits in order to ensure the size of the nucleus and the strength of the welded joint. In order to obtain a certain strength of the welded joint, you can use high current and a short time (strong conditions, also known as hard specification), or small current and a long time (weak conditions, also known as soft specification). The choice of hard or soft conditions depends on the properties of the metal, its thickness and the power of the welding machine used. For different properties and thickness of the metal required current and time, there is an upper and lower limit, the use of this as a guide.
Electrode pressure on the total resistance between the two electrodes R has a significant effect, as the electrode pressure increases, R significantly reduced, while the magnitude of the increase in welding current is not large enough to affect the reduction in heat production caused by the decrease in R. Therefore, the strength of the welded joint is always reduced with the increase in welding pressure. The solution is to increase the welding pressure at the same time, increase the welding current.
Since the contact area of the electrode determines the current density, and the resistivity and thermal conductivity of the electrode material relates to the generation and dissipation of heat, the shape and material of the electrode have a significant effect on the formation of the molten core. With the deformation and wear of the electrode tip, the contact area increases and the strength of the welded joint will decrease.
Working Principle
Spot Welder
Spot Welder adopts the principle of double-sided double-point overcurrent welding, when the two electrodes pressurize the workpiece so that the two layers of metal in the two electrodes under the pressure of the formation of a certain contact resistance, while the welding current from one electrode through the other electrode in the two contact resistance point to form an instantaneous thermal fusion, and the welding current instantly from the other electrode along the two workpiece to form a circuit. The welding current instantly flows from the other electrode along the two workpieces to form a circuit to this electrode, which does not hurt the internal structure of the workpieces to be welded.
Spot welding process for the opening of the cooling water; the surface of the weldment is cleaned, assembled accurately, sent between the upper and lower electrodes, applying pressure to make good contact; energized so that the two workpieces in contact with the surface of the heat, local melting, the formation of molten core; power off to maintain the pressure, so that the molten core cooled and solidified under pressure
to form the welded joints; to remove the pressure, take out the workpiece. Welding current, electrode pressure, energizing time and electrode working surface size and other spot welding process parameters have a significant impact on welding quality.
Spot welding machine using positive and negative poles in the instantaneous short-circuit generated by the high temperature arc to melt the electrode on the solder and the material to be welded, to achieve the purpose of making them combined. The structure of the welding machine is very simple, to put it bluntly is a high-power transformer, 220V AC power into low voltage, high current power supply, can be DC or AC. Welding transformer has its own characteristics, that is, the characteristics of a sharp drop in voltage.
After the electrode ignition voltage drop, the regulation of the working voltage of the welding machine, in addition to the primary 220/380 voltage conversion, the secondary coil also has a tap to change the voltage, while there is also a core to regulate the core, adjustable core. Welding machine is generally a high-power transformer, the use of the principle of inductance made. Inductance in the connection and disconnection will produce a huge voltage change, the use of positive and negative poles in the instantaneous short-circuit generated by the high-voltage arc to melt the solder on the electrode. To achieve the purpose of making them combined.
Spot welding is the weldment assembly joints, and pressed between the two electrodes, the use of resistance heat melting base metal, the formation of welded joints resistance welding method. Spot welding more
For the connection of thin plates, such as aircraft skin, aviation engine fire smoke tube, automobile cab shell. Spot welding machine welding transformer is spot welding electrical appliances, its secondary only one loop circuit. The upper and lower electrodes and electrode arms are used to conduct welding current as well as to transfer power. Cooling water circuit through the transformer, electrode and other parts, so as not to heat welding, should first pass cooling water, and then turn on the power switch. The quality of the electrode directly affects the welding process, welding quality and productivity. Electrode materials commonly used purple copper, cadmium bronze, chrome bronze, etc. made; electrode shape a variety of different, mainly based on the shape of the weldment to determine. Installation of the electrode, pay attention to the upper and lower electrode surface to keep parallel; electrode plane to keep clean, commonly used emery cloth or file trimming.
Welding CycleThe welding cycle of spot and projection welding consists of four basic stages (spot welding process):
(1) Pre-pressurization stage - the electrode is lowered to the stage of current turn-on to ensure that the electrode is pressed against the workpiece, so that there is proper pressure between the workpiece.
(2) Welding time - welding current passes through the workpiece and heat is generated to form a molten core.
(3) Maintenance time - the welding current is cut off and the electrode pressure is maintained until the nucleus has solidified to sufficient strength.
(4) Rest time - the electrode begins to lift until the electrode begins to fall again, starting the next welding cycle. In order to improve the performance of a welded joint, it is sometimes necessary to add one or more of the following to the basic cycle:
(1) Increase the pre-pressure to eliminate gaps between thicker workpieces for a tight fit.
(2) Increase the plasticity of the metal with a preheat pulse to make it easier for the workpieces to fit tightly and prevent spattering; this is done in the case of bump welding to make multiple bumps in uniform contact with the flat plate prior to energizing the weld to ensure that the heating is consistent from one point to the next.
Technical Parameters
Spot Welder
Rated Capacity: KVA (kVA) 402525161010
Power Voltage V (volts): 380
Primary Voltage A (amp): 1056565422626
Secondary Voltage V (volts): 4.3-6.52.4- 41.81-3.82-3.41.80-3.21.52-2.62
Regulation level level: 778777
Rated regulation level level: 667666
Welding points/hour: 600-80006008000720900900
Mild steel plate welding thickness rating mm (mm): 1.5+1.5-4+4 1+1-3+31+1-2+20.5+0.5-2+20.3+0.3-1.5+1.50.3+0.3-1.5+1.5
Reduced Temporary Load Ratio Maximum mm (mm): 4.5+4.53.5+3.52.5+2.52.5+2.52+2.52+22+2
Mild steel garden bar cross weld welding range (diameter) mm (mm): 3+3-10+103+3-8+81+1-3+31+1-6+62+2-5+51.5+1.5-4+4
Load sustaining rate %: 202015151510
Electrode arm outstretched length mm (mm): 510400450400400350
Electrode arm spacing mm (mm): 120-360150150150150150150
Upper electrode working stroke mm (mm): 252020202015
Cooling water consumption kg: 200450400400350
Maximum electrode pressure KN: 0.81.51.51.51.00.7
Weight kg: 24516516514013063
Mechanical use
Spot welder
Spot welder use:
1. Welding should be done by firstly adjusting the electrode rod position so that the electrodes are just pressed to the weldment when the electrode arm Keep parallel to each other.
2, the selection of current regulating switch level can be selected according to the thickness of the weldment and material. After power on the power indicator should be bright, electrode pressure size can be adjusted spring pressure nut, change the degree of compression and obtain.
3, in the completion of the above adjustments, you can first turn on the cooling water and then turn on the power to prepare for welding. Welding process procedures: the weldment is placed between the two electrodes, step on the foot pedal, and make the upper electrode and the weldment contact and pressure, continue to depress the foot pedal, the power contact switch on, so the transformer began to work the secondary circuit energized to make the weldment heating. When welding for a certain period of time after the release of the foot pedal when the electrode rises, through the spring tension first cut off the power supply and then return to its original state, the single-point welding process comes to an end.
4, weldment preparation and assembly: steel weldments before welding to remove all the dirt, oil, oxidized skin and rust, hot rolled steel, it is best to weld the first after pickling, sandblasting, or use a wheel to remove oxidized skin. Without cleaning the weldments can be spot welding, but seriously reduce the service life of the electrode, while reducing the productivity and quality of spot welding. For a thin coating of low carbon steel can be welded directly.
In addition, the user can refer to the following process data when using:
1, welding time: in the welding of medium and low carbon steel, this welder can be utilized in the strong specification welding method (instantaneous energization) or weak specification welding method (long-time energization). In mass production should be used in the strong specification welding method, it can improve productivity, reduce power consumption and reduce the workpiece deformation.
2, welding current: welding current is determined by the size of the weldment, thickness and contact surface. Usually the higher the metal conductivity, electrode pressure, welding time should be shorter. At this time, the required current density also increases.
3, electrode pressure: electrode pressure on the weldment is designed to reduce the contact resistance of the welded joint, and to ensure that the formation of welded joints when the pressure required.
4, the shape and size of the electrode: electrode machined from chrome zirconium copper. Electrode contact surface diameter is roughly:
δ ≤ 1.5mm, the electrode contact surface diameter, 2 δ + 3 (mm)
δ ≥ 2mm, the electrode contact surface diameter, 1.5 δ + 5 (mm)
δ - the thickness of the thinner of the two pieces of the thickness of the piece (mm)
Electrodes should not be too small in diameter. To avoid excessive heat generation and rapid wear and tear.
5, the layout of the welding point:
The smaller the distance between the welding point, the current shunt phenomenon increases, and make the pressure at the spot welding is reduced, thus weakening the strength of the welding point. For mild steel or stainless steel weld center distance A ì 16.1 δ (mm)
Installation and maintenance
Spot welder
Welder must be properly grounded before use to protect personal safety. Before using the welding machine to use 500V megohmmeter to test the high voltage side of the welding machine and the insulation resistance between the casing is not less than 2.5 megohm before energizing. Maintenance should first cut off the power supply before opening the box for inspection. Welding machine first water after welding, no water is strictly prohibited. Cooling water should be guaranteed in the 0.15-0.2MPa water pressure under the supply of 5-30 ℃ industrial water. Winter welding machine work is completed after the application of compressed air will be blown out of the pipeline water to avoid freezing water pipes.
Welder leads should not be too thin and long, welding voltage drop shall not be greater than 5% of the initial voltage, the initial voltage can not deviate from the power supply voltage ± 10%. Welding machine operation should wear gloves, aprons and protective glasses to avoid sparks flying out of the scalding. The sliding part should be well lubricated, and metal spatter should be removed after use. The new welding machine should be used 24 hours after the start of each part of the screws should be fastened once, especially pay attention to the copper soft link and the electrode between the coupling screws must be fastened, after use should often remove the electrode rod and electrode arm of the oxides between the electrode to ensure good contact.
Welder use if you find the AC contactor suction is not real, indicating that the grid voltage is too low, the user should first solve the problem of power supply, power supply is normal before use. It should be noted that the newly purchased welding machine half a month if the quality of the main part of the problem, you can replace the new welding machine or replace the main part. The main part of the welding machine is guaranteed for one year, and maintenance service is provided for a long time. Generally speaking, after the user notifies the factory, the service will be in place within three to seven days according to the distance. Damage to the welder caused by the user is not covered by the warranty. Wear parts, consumable parts are not under warranty.
Since the contact area of the electrode determines the current density, and the resistivity and thermal conductivity of the electrode material relates to the generation and dissipation of heat, the shape and material of the electrode have a significant effect on the formation of the molten core. With the deformation and wear of the electrode tip, the contact area increases and the strength of the welded joint will decrease. Oxides, dirt, oil and other impurities on the surface of the workpiece increase the contact resistance. An excessively thick oxide layer may even prevent current from passing through. Localized conduction, due to excessive current density, then spatter and surface burns. The presence of an oxide layer also affects the unevenness of the heating of the individual weld joints, causing fluctuations in weld quality. Therefore, thoroughly clean the surface of the workpiece is to ensure that the necessary conditions for obtaining high-quality joints
Troubleshooting
Spot Welder
1, step down the foot pedal welder does not work, the power supply indicator lamp does not light:
a. Check whether the power supply voltage is normal; check whether the control system is normal.
b. Check whether the foot switch contacts, AC contactor contacts, split shift switch is in good contact or burned.
2, the power indicator light, the workpiece pressure does not weld:
a. Check whether the foot pedal travel is in place, whether the foot switch contact is good.
b. Check whether the pressure lever spring screw is properly adjusted.
3. Undue spattering during welding:
a. Check whether the electrode head is badly oxidized.
b. Check whether the welding workpiece is seriously rusted poor contact.
c. Check whether the adjustment switch is too high gear.
d. Check whether the electrode pressure is too small and whether the welding program is correct.
4, the welded joint indentation is serious and extrusion:
a. Check whether the current is too large.
b. Check whether the welding workpiece is uneven.
c. Check whether the electrode pressure is too high and whether the electrode head shape and cross-section are suitable.
5, welding workpiece strength is not enough:
a. Check whether the electrode pressure is too small, check whether the electrode rod is fastened well.
b. Check whether the welding energy is too small, whether the welding workpiece is badly rusted, so that the welded joint contact is poor.
c. Check whether there is too much oxide between the electrode head and electrode rod, electrode rod and electrode arm.
d. Check whether the cross-section of the electrode head is enlarged due to wear and tear resulting in reduced welding energy.
e.Check for severe oxidation of the electrode and copper soft joint and bonding surface.
6, welding AC contactor ringing abnormal:
a. Check whether the AC contactor inlet voltage in welding is lower than its own release voltage of 300 volts.
b. Check whether the power supply lead is too thin and too long, resulting in too much line voltage drop.
c. Check to see if the net voltage is too low for normal operation.
d. Check if the main transformer has a short circuit, causing too much current.
7, the welder appears overheating phenomenon:
a. Check whether the insulation resistance between the electrode holder and the body is bad, resulting in a local short circuit.
b. Check whether the inlet water pressure, water flow, water supply temperature is appropriate, check whether the water circuit system is clogged with dirt, resulting in overheating of the electrode arm, electrode rod and electrode head due to poor cooling.
c. Check whether the contact surface of copper soft link and electrode arm, electrode pole and electrode head are oxidized seriously, resulting in increased contact resistance and serious heating.
d. Check whether the cross-section of the electrode head increases too much due to wear and tear, causing the welder to overload and heat up.
e. Check whether the welding thickness and load duration rate are excessive, causing the welder to overload and heat up.
Safe operating procedures
I. Preparation before welding
1. Before work, you must remove the upper and lower two electrodes of oil and dirt. Energized to check the electrical equipment, operating mechanism, cooling system, gas system and the body shell for leakage.
2. The room temperature should not be lower than 15 ℃.
3. Before starting, turn on the control line transfer switch and welding current switch, insert the gate position of the pole regulating switch, turn on the water supply, gas supply, control box on the adjustment knob. Electrode contacts to keep clean.
4. The use of pneumatic pedal control spot welder, should check the pipeline without air leakage and impurity blockage.
Two, welding in the notes
1. welding machine work, gas circuit, water cooling system is smooth. Gas should not contain water. Drainage temperature does not exceed 40 ℃, the flow rate is adjusted according to regulations.
2. Bearing hinge and cylinder piston, liner ring should be lubricated regularly.
3. The upper electrode's working stroke adjustment nut (under the cylinder body) must be tightened. Electrode pressure can be adjusted by rotating the decompression valve handle according to the requirements of welding specifications.
4. It is strictly prohibited to increase the fuse in the ignition circuit to prevent damage to the ignition tube and silicon rectifier. When the load is too small, the ignition tube arc can not occur, it is strictly prohibited to close the ignition circuit of the control box.
Three, after welding precautions
1. welding machine stop working, should first cut off the power supply, gas, and finally shut down the water supply, remove debris and welding slag spatter end.
2. Welding machine for a long time out of service, should not paint the active parts coated with anti-rust oil finger. Monthly energized heating 30min. replacement of the gate tube should also be preheated for 30min, normal operation of the control box preheating not less than 5min.
Specific classification of spot welder
Spot welder can be divided into:
According to the use of sub-parts, there are universal (universal), special-purpose
According to the number of welding points welded at the same time sub-partition, there are single-point, double-point type, Multi-point type;
According to the conductive mode, there are single-side, double-side;
According to the transmission mode of the pressurizing mechanism, there are foot-operated, motor-cam, pneumatic, hydraulic, composite (pneumatic-hydraulic);
According to the operation of the characteristics of the points, there are non-automatic, automated;
According to the installation of the method of points, there are stationary, mobile
According to the installation method, there are fixed, mobile (hanging);
According to the welding machine's movable electrode (usually the upper electrode) moving direction, there are vertical stroke (electrode for straight-line movement), arc stroke;
According to the supply of electricity, there are frequency welding machine (using 50 Hz AC power supply), pulse welder (DC pulse welder, storage welder, etc.), inverter welder (e.g., low-frequency welding machine).
Spot Welder
Spot Welder in accordance with the use of points, there are universal (universal), special-purpose; in accordance with the number of simultaneous welding joints points, there are single-point, double-point, multi-point; in accordance with the conductivity of points, there are single-side, double-side; in accordance with the pressurized mechanism of the transmission mode points, there is a foot-operated, motor-cam, pneumatic, hydraulic, composite (gas-hydraulic); in accordance with the characteristics of operation points, there are non-automatic, non-automatic, non-hydraulic (gas-hydraulic). The characteristics of the operation points, there are non-automatic, automated; according to the method of installation points, there are fixed, mobile or lightweight (hanging); according to the welding machine's movable electrode (usually on the electrode) the direction of movement points, there are vertical stroke (electrode for straight-line movement), arc stroke; according to the supply of electricity points, there is a frequency welding machine (using 50 Hz AC power supply), pulse welding machine (DC pulse welding machine, Energy storage welder, etc.), frequency welding machine (such as low-frequency welding machine). When the workpiece and the electrode are certain, the resistance of the workpiece depends on its resistivity. Therefore, the resistivity is an important property of the welded material. Resistivity of the metal with high electrical conductivity is poor (such as stainless steel), low resistivity of the metal with good electrical conductivity (such as aluminum alloy). Therefore, spot welding stainless steel heat easy and difficult to dissipate heat, spot welding aluminum alloy heat difficult and easy to dissipate heat. Spot welding, the former can be used in smaller currents (thousands of amperes), while the latter must use a large current (tens of thousands of amperes). Resistivity depends not only on the type of metal, but also on the state of heat treatment, processing and temperature of the metal.
Spot welding machine working principle
Spot welding process for the opening of the cooling water; the surface of the weldment cleaned, assembled accurately, sent to the upper and lower electrodes between the pressure to make good contact; energized so that the two pieces of work contact surface heat, local melting, the formation of nuclei; power off to maintain pressure, so that the nuclei under pressure to cool the formation of welded joints; remove the pressure, remove the workpiece. Welding current, electrode pressure, energizing time and electrode working surface size and other parameters of the spot welding process has a significant impact on the welding quality. Spot welding machine using positive and negative poles in the instantaneous short-circuit of the high temperature arc to melt the electrode on the solder and the welded material, to achieve the purpose of making them combined. The structure of the welding machine is very simple, to put it bluntly, it is a high-power transformer, will 220V AC power into low voltage, high current power supply, can be DC or AC. Welding transformer has its own characteristics, that is, the characteristics of a sharp drop in voltage. After the welding rod ignition voltage drop, the welding machine working voltage regulation, in addition to a 220/380 voltage conversion, the secondary coil also has a tap to change the voltage, while there is also the core to adjust the core, adjustable core. Welding machine is generally a high-power transformer, the use of the principle of inductance made. Inductance in the connection and disconnection will produce a huge voltage change, the use of positive and negative poles in the instantaneous short-circuit generated by the high-voltage arc to melt the solder on the electrode. To achieve the purpose of making them combined. Pedal spot welder spot welding is a weldment assembly joint, and pressed between the two electrodes, the use of resistance heat to melt the base metal, the formation of welded joints resistance welding method. Spot welding is mostly used for thin plate connection, such as aircraft skin, aviation engine fire smoke tube, automobile cab shell. Spot welding machine welding transformer is spot welding electrical appliances, its secondary only one loop circuit. The upper and lower electrodes and electrode arms are used to conduct welding current as well as to transfer power. Cooling water circuit through the transformer, electrode and other parts, so as not to heat welding, should first pass cooling water, and then turn on the power switch. The quality of the electrode directly affects the welding process, welding quality and productivity. Electrode materials commonly used purple copper, cadmium bronze, chrome bronze, etc. made; electrode shape a variety of different, mainly based on the shape of the weldment to determine. Installation of electrodes, pay attention to the upper and lower electrode surface to maintain parallel; electrode plane to keep clean, commonly used emery cloth or file trimming. Welding cycle spot welding and convex welding welding cycle consists of four basic stages (spot welding process): (1) pre-pressure stage - electrode down to the current on stage, to ensure that the electrode is pressed against the workpiece, so that there is appropriate pressure between the workpiece. (2) Welding time - the welding current passes through the workpiece, generating heat to form a molten core. (3) Maintenance time - The welding current is cut off and the electrode pressure continues to be maintained until the nucleus solidifies to sufficient strength. (4) Rest time - the electrode begins to lift until the electrode begins to fall again, starting the next welding cycle. In order to improve the performance of welded joints, it is sometimes necessary to add one or more of the following to the basic cycle:(1) Increase the pre-pressure to eliminate gaps between thicker workpieces for a tight fit. (2) increase the plasticity of the metal with a preheat pulse, so that the workpiece is easy to close fit, prevent spatter; convex welding this can be done so that multiple bumps in the weld with the flat plate before the power to ensure that the points are heated consistently