Views: 7 Author: DURMAPRESS Publish Time: 2021-09-16 Origin: DURMAPRESS
hand held fiber laser welding machine Advantages of lasers
Compared with the traditional arc welding process, the laser beam joint has many advantages:
· Selective energy application in small area: reduced thermal stress and reduced heat affected zone, very low distortion.
· Narrow joint and smooth surface: reduce or even eliminate reprocessing fiber laser welding machine.
· High strength combined with low welding volume: the welded workpiece can withstand bending or hydroforming.
· Easy integration: can be combined with other production operations, such as alignment or bending.
· Only one side of the seam needs to be approached.
· High process speed to shorten processing time.
· Especially suitable for automation technology.
· Good program control: machine tool control and sensor system to detect process parameters and ensure quality.
· The laser beam can produce solder joints without touching the workpiece surface or applying force to the workpiece.
Welding and brazing metals
In heat conduction welding, the surface is melted
Laser beams can be used to join workpieces or create deep welds on metal surfaces, in combination with conventional welding methods or for brazing.
Heat conduction welding
In heat conduction welding, a laser beam melts matching parts along a common joint. The molten material flows together and solidifies, producing a smooth, round weld that does not require any additional grinding or finishing.
Deep penetration produces a vapor-filled hole, or pinhole effect
Heat conduction welding depths range from only a few tenths of a millimeter to a millimeter. The thermal conductivity of the metal limits the maximum weld depth, and the weld spot is always wider than it is deep.
A cross section of laser welding seen under a microscope
If the heat does not dissipate quickly, the processing temperature will rise above the gasification temperature, the metal vapor forms, the welding depth increases dramatically, and the process becomes deep fusion welding.
2 deep penetration
Deep fusion welding requires an extremely high power density of about 1 MW/cm2. As the laser beam melts the metal, it creates steam, which puts pressure on the molten metal and partially displaces it. Meanwhile, the material continues to melt, creating a deep, narrow, vapor-filled hole known as the pinhole effect. As the laser beam travels along the weld, the holes move, and the molten metal circulates through the holes and solidifies in their tracks, producing a deep, narrow weld with a uniform internal structure that may be ten times larger than the weld width, 25mm or more.
Deep fusion welding is characterized by high efficiency and fast welding speed, small heat-affected zone and minimal distortion. It is often used in applications requiring deep fusion welding or simultaneous welding of multi-layer materials.
Active gas and protective gas
Active and protective gases assist the laser beam during welding.
Active gas is used for CO2 laser welding to prevent plasma clouds forming on the workpiece surface and blocking the laser beam.
Shielding gas is used to protect the welding surface from ambient air and the flow of shielding gas to the workpiece is non-turbulent (laminar flow).
4 Filling materials
Filler material is usually added in silk or powder to the point to be joined. The role of:
1. Fill gaps that are too wide or irregular to reduce the amount of work required for joint preparation.
2. Fillers are added to the molten metal in a specific form of composition to change the welding suitability, strength, durability and corrosion resistance of the material.
Composite welding technology
Composite welding technology refers to the combination of laser welding and other welding methods. Compatible processes are MIG(inert gas welding) or MAG(reactive gas welding), TIG(tungsten inert gas welding) or plasma welding. Composite welding technology is faster and less deformed than single MIG welding.
In laser brazing, matching parts are joined together by filler material or solder. The melting temperature of the solder is lower than that of the base metal. During brazing, only the solder is melted and only the matching parts are heated. The solder melts into the gap between the parts and joins the workpiece surface (diffusion bonding).
Brazing joint strength and solder material, joint surface smooth clean, no need for finishing, often used in car body processing, such as trunk cover or roof.
Laser welding using filler wire, active gas and protective gas
Sensors are used to detect and adjust certain parameters, including the working distance, the position of the laser beam in the joint gap, the adjustment Angle of the optical lens, and the amount of filler material, to ensure the welding quality during the processing of parts and detect inferior parts.
1 Weld tracking
When the laser beam is used to weld butt joints in the material, track the joint gap track and position the laser beam correctly to ensure that the laser beam remains at the same position in the joint gap.
Keep monitoring the process
Sensor systems can be combined to achieve more comprehensive monitoring of the welding process. Includes "before welding", "in welding" and "after welding" sensors.
Pre-welding sensors are located in front of the solder joint to track the weld and locate the laser beam. Welding sensors use a camera or diode to detect the welding process during welding. Camera-based systems analyze keyholes and welding pools. Diode systems can detect the intensity of processed light, thermal radiation, or reflected laser. After welding, sensors check the finished solder joints to determine whether the solder joints meet the quality requirements.
Sensors rely on programmed limits to distinguish between good and bad parts.
Laser welding machine
The design of laser welding machine depends on many factors, such as workpiece shape, welding geometry, welding type, production capacity, degree of production automation, as well as technology and materials and so on.
1 Manual welding
Manual workstations are often used to weld small workpieces, such as jewelry or repair tools.
Sometimes the laser beam needs to be welded along a single moving axis. Such as using a seam welding machine or a pipe welding system for pipe welding or seam welding.
3. Systems and robots
Laser beams are usually connected to three-dimensional parts characterized by three-dimensional welded geometry. A five-axis coordinate based laser unit and a set of removable optical fittings are used.
4 Scanning galvanometer or remote welding
The scanning galvanometer guides the laser beam at a great distance from the workpiece, whereas in other welding methods the optical lens guides the laser beam at a great distance from the workpiece.
Scanning galvanoscopes rely on one or two mobile mirrors to quickly position the laser beam, so that the time required to reset the beam between welds is close to zero, thus improving productivity, suitable for the production of a large number of short welds, and can optimize the welding sequence to ensure minimal heat input and distortion.
Remote welding system
The remote welding system can be implemented in two ways. The first is a remote welding system. The workpiece is placed in the working area under the scanning optical galvanometer and then welded. When welding a large number of parts in a short period of time, parts are continuously transported by a machine under an optical mirror, a process known as flying welding.
The second is that the robot carrying the scanning optical mirror performs a large amount of movement, and at the same time, the scanning optical mirror ensures the precise positioning of the laser beam as it moves back and forth along the workpiece. The machine controls the overlapping movement of the synchronous robot and the scanning optical lens. It measures the precise spatial position of the robot within a few millimeters, and the control system compares the measured position with the program path. If a deviation is detected, it is compensated by scanning an optical galvanometer.
Laser welding will become easier
The laser welding process opens up a wide range of application possibilities. High quality, minimal reprocessing and low cost efficiency become a strong argument for vigorously promoting laser welding technology. In the future, laser welding technology will become as mature as laser cutting.