Pros And Cons of All The Different Seam Tracking Solutions (2)

  • By:Iris Liang
  • Date:2021/11/16

4. Tactile seam tracking

Tactile is a physical contact probe that touches the material. Haptics are often used in hard automation and some laser brazing applications, rather than seam tracking applications for 6-axis robots. It installs a tip or probe inside the welding joint, and detects the deviation of the edge in contact with the original source, and adjusts its cross slider accordingly to position it correctly on the weld.

Tactile seam tracking has a very simple operation function and can be applied to various processes, including sub-arc, arc-opening and brazing, which makes it a very versatile form of seam tracking. The sense of touch is also not limited by any material, so you can touch the seams, from stainless steel to aluminum, without any impact on the system.

Maintenance is an important part of keeping the tactile tracking system working properly. Because the tip is in constant contact with the engagement surface, component wear often occurs in the haptic system. When its tip wears out and becomes shorter, it will bring your welding tool forward and close to the joint, which can cause poor welding or completely damage the front end of the torch. It is very important to check whether the probe is worn or not to ensure that the probe is properly separated from the torch to obtain high-quality welding.

Haptic solutions should be checked and maintained more frequently than non-contact solutions for other items such as welding spatter and cable management conditions.

Tactile seam tracking solutions are also not suitable for nail welding. As is generally recommended, the nail can lift the probe over the tack welding and direct the arc in the same direction, instead of letting the torch weld through the tack.

Tactile seam tracking is also not suitable for adaptive. These types of systems follow the joint line and do not consider mismatches or gap sizes due to tools. Area calculation is also impossible. A tactile probe will lock in a groove and follow it with minimal deviation. A sufficiently large change in the groove or a large enough spot weld can cause the probe to escape its desired track.

For welding profiles like butt welds, it is difficult to track tactile welds without gaps. Non-linear welding forces the probe to move sharply in one direction, which is not ideal for tactile seam tracking applications; it is suitable for large cylindrical welding or pipe welding.

Travel speed is another limitation of tactile seam tracking because it usually moves at a lower speed, which slows down your cycle time.

Comparing tactile and vision-based seam tracking is a contact-based approach and another non-contact problem. Although haptic seam tracking is a mechanical setting, it is usually a lower upfront capital investment. The haptic tracking system in open and secondary arc applications requires more maintenance because it is a mechanical process that has a long-term Can make it a less cost-effective solution. The sensitivity of the measuring body and the continuous wear and tear of the components.

5. 3D laser weld tracking

The 3D laser seam tracking system is also called optical or visual seam tracking and uses the principle of laser triangulation. The laser seam tracking system can be used on hardware automation and robotic systems, and the correct software package can be used.

Conceptually, laser seam tracking involves a laser beam emitted from the device, hitting the surface, reflecting off the surface, bounced back to the sensor, and the sensor picks up the location where the beam hits. Therefore, through laser seam tracking, the sensor can know the distance between the laser transmitter and the sensor on the camera, so that it can triangulate the material that it bounces back.

Essentially, you can get the Z (height) and Y (lateral) images of the joint, so the sensor knows the image it bounces from the X (distance) size of the light away from the sensor, and its features in the Y-direction field of view Choose whether it is positive or negative.

Laser weld tracking does not know the X direction or the length of the part. This is why you use the equipment in conjunction with a control system, which defines the X value-a process called calibration. After calibration, the seam tracking system will identify the X, Y and Z positions throughout the welding process.

Any seam tracking solution for the welding process will increase the cycle time, but laser seam tracking increases the cycle time the least-usually the welding cycle per scan is about a quarter of a second. It can also move the fastest. Optical tracking can reach 200 inches per minute, so if high travel speeds are required, it will not limit the robot or gantry speed. Laser welding seam tracking can also be used in processes other than welding, such as gluing, spraying, and polishing.

Laser has a unique advantage over TAST because it allows the device to run dry on the part or view it offline. Since the tracking is only based on the imaging of the part, inconsistencies in materials such as rust, scales or even tack have little effect on laser weld tracking.

The gap for laser weld tracking is a limitation. The direction of travel is another consideration because the sensor must always guide the welding path. This can lead to robot arrival problems, torch angle problems, and careful consideration of the tooling and design of the components.

Generally, the only difficult to apply laser weld tracking is shiny materials. The reason is that whenever laser light is emitted from a material, it must be reflected. Consider the different weld joint types and how they reflect the laser beam depending on the material. In the knee joint, it reflects directly back. If it is a V-joint, it will not only reflect the straight back, but also reflect the opposite angle it reflects-almost like a disco ball. In these cases, it is difficult for the sensor to determine which beam is reflected back to be the correct beam. You have a lot of fake beams coming back, it looks like a crosshair because you get a lot of reflections.

Laser welding seam tracking cannot fully track material-joint combinations such as fillet welds of aluminum alloy diamond plates. Other combinations, such as stainless steel inner corners with mirror finish, are also very difficult surfaces and joints for seaming tracks. Although optical systems can be used to track these combinations, special familiarity with laser slit tracking sensors is required to repeat this.

If you want to know more about the detailed parameters or processes of the stainless steel industrial welded pipe production unit and the supporting weld tracking, please feel free to contact Hangao Tech (SEKO Machinery) !




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